changelog: past tense

Signed-off-by: Ramon Petgrave <ramon.petgrave64@gmail.com>

Author: ramonpetgrave64

CHANGELOG.md

@@ -36,7 +36,7 @@ All versions prior to 0.9.0 are untracked.
   [sigstore/timestamp-authority](https://github.com/sigstore/timestamp-authority)
   [#1377](https://github.com/sigstore/sigstore-python/pull/1377)
 
-* Tests: Update the `staging` and `sign_ctx_and_ident_for_env` fixtures to use the new methods
+* Tests: Updated the `staging` and `sign_ctx_and_ident_for_env` fixtures to use the new methods
   for generating a `SigningContext`.
   [#1409](https://github.com/sigstore/sigstore-python/pull/1409)