pin cargo-audit version (aws-observability#286)

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*Description of changes:*
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aws-observability#285

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Author: ezhang6811

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@@ -36,7 +36,7 @@ ARG TARGETARCH
 RUN if [ $TARGETARCH = "amd64" ]; then rustup component add rustfmt && cargo fmt --check ; fi
 
 # Audit dependencies
-RUN if [ $TARGETARCH = "amd64" ]; then cargo install cargo-audit && cargo audit ; fi
+RUN if [ $TARGETARCH = "amd64" ]; then cargo install cargo-audit --locked && cargo audit ; fi
 
 
 # Cross-compile based on the target platform.