Update snafu requirement from 0.7 to 0.8 (#65)

Updates the requirements on [snafu](https://github.com/shepmaster/snafu)
to permit the latest version.
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a
href="https://github.com/shepmaster/snafu/blob/main/CHANGELOG.md">snafu's
changelog</a>.</em></p>
<blockquote>
<h2><a
href="https://github.com/shepmaster/snafu/releases/tag/0.7.5">0.7.5</a>
- 2023-07-09</h2>
<h3>Added</h3>
<ul>
<li>The <code>CleanedErrorText</code> iterator can be used to remove
redundant
parts from the messages that many errors duplicate from their
underlying sources. This is the same behavior as <code>Report</code>,
but can
be used in contexts other than console output, such as when
reporting an error in structured output like HTML or JSON.</li>
</ul>
<h3>Fixed</h3>
<ul>
<li>The documentation for the compatability feature flags now mentions
<code>rust_1_39</code> and shows the correct default state of
<code>rust_1_61</code>.</li>
</ul>
<h2><a
href="https://github.com/shepmaster/snafu/releases/tag/0.7.4">0.7.4</a>
- 2022-12-19</h2>
<h3>Changed</h3>
<ul>
<li><code>Report</code> and the <code>[report]</code> macro now remove
redundant parts from
the messages that many errors duplicate from their underlying
sources.</li>
</ul>
<h2><a
href="https://github.com/shepmaster/snafu/releases/tag/0.7.3">0.7.3</a>
- 2022-10-20</h2>
<h3>Fixed</h3>
<ul>
<li>The macro no longer generates invalid code when implicitly-generated
types (such as backtraces) were used in conjunction with
<code>#[snafu(source(from))]</code> and the type before transformation
does not
implement <code>std::error::Error</code>.</li>
</ul>
<h2>[0.7.2] - 2022-10-09</h2>
<h3>Added</h3>
<ul>
<li>
<p><code>Report</code> can be returned from <code>main</code> or test
functions to provide a
user-friendly display of errors.</p>
</li>
<li>
<p>A cheat sheet for the most common <code>#[snafu(...)]</code>
attribute usages
has been added to the <code>Snafu</code> macro's documentation.</p>
</li>
<li>
<p>Optional support for using the standard library's
<code>std::backtrace::Backtrace</code> type via the
<code>backtraces-impl-std</code></p>
</li>
</ul>
<!-- raw HTML omitted -->
</blockquote>
<p>... (truncated)</p>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/shepmaster/snafu/commit/d833d11f7a1c888a9e58745106035b58333fcd2f"><code>d833d11</code></a>
Release 0.7.5</li>
<li><a
href="https://github.com/shepmaster/snafu/commit/742a212cd335e4f9527d4025cc7ba6979273f5e9"><code>742a212</code></a>
Update the changelog</li>
<li><a
href="https://github.com/shepmaster/snafu/commit/e04a77c149e8deacf83c00704abee66d50fd46c2"><code>e04a77c</code></a>
Merge pull request <a
href="https://redirect.github.com/shepmaster/snafu/issues/386">#386</a>
from shepmaster/compat-docs</li>
<li><a
href="https://github.com/shepmaster/snafu/commit/ecd6c82d49f957a4a548d9a343302c4a01083027"><code>ecd6c82</code></a>
Merge pull request <a
href="https://redirect.github.com/shepmaster/snafu/issues/383">#383</a>
from shepmaster/cleaned-error-text</li>
<li><a
href="https://github.com/shepmaster/snafu/commit/f00b5c0476222517b71cc3054ea8cbd6084a3538"><code>f00b5c0</code></a>
Correct documented default state for the <code>rust_1_61</code> feature
flag</li>
<li><a
href="https://github.com/shepmaster/snafu/commit/93f55e2d1c0908d0ff5df5a08d9f77d64d0c104d"><code>93f55e2</code></a>
Document the <code>rust_1_39</code> feature flag</li>
<li><a
href="https://github.com/shepmaster/snafu/commit/e4e57eacec684c99738230a2b95b6b98c39a0816"><code>e4e57ea</code></a>
Extract an iterator that cleans redundant nested error text</li>
<li><a
href="https://github.com/shepmaster/snafu/commit/d993c94e999f7c1201b11e750b803a30b7588cc3"><code>d993c94</code></a>
Merge pull request <a
href="https://redirect.github.com/shepmaster/snafu/issues/385">#385</a>
from Enet4/fix/update-compile_error-messages</li>
<li><a
href="https://github.com/shepmaster/snafu/commit/2bf38fb974dde31d2fb47232adc212f70f9b44a0"><code>2bf38fb</code></a>
Update compile_error test snapshots</li>
<li><a
href="https://github.com/shepmaster/snafu/commit/00bba4b4243a340cdcafc7a8478f9e26b860692d"><code>00bba4b</code></a>
Release 0.7.4</li>
<li>Additional commits viewable in <a
href="https://github.com/shepmaster/snafu/compare/0.7.0...0.7.5">compare
view</a></li>
</ul>
</details>
<br />


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</details>

Cargo.toml

@@ -28,7 +28,7 @@ ark-std = { version = "0.4.0", default-features = false }
 base64 = "0.21"
 crc-any = { version = "2.4.1", default-features = false }
 serde = { version = "1.0", optional = true, features = ["derive"] }
-snafu = { version = "0.7", features = ["backtraces"] }
+snafu = { version = "0.8" }
 tagged-base64-macros = { version = "0.3.3", path = "macros", default-features = false }
 
 # Command line argument processing