Bump Rust to match monorepo (1.54 and 2021-08-02 nightly) (#2389)

Author: joncinque

ci/rust-version.sh

@@ -18,13 +18,13 @@
 if [[ -n $RUST_STABLE_VERSION ]]; then
   stable_version="$RUST_STABLE_VERSION"
 else
-  stable_version=1.53.0
+  stable_version=1.54.0
 fi
 
 if [[ -n $RUST_NIGHTLY_VERSION ]]; then
   nightly_version="$RUST_NIGHTLY_VERSION"
 else
-  nightly_version=2021-06-09
+  nightly_version=2021-08-02
 fi