RUST-1529 Use AWS SDK to get credentials

.evergreen/compile-only.sh

@@ -9,6 +9,11 @@ source ./.evergreen/env.sh
 if [ "$RUST_VERSION" != "" ]; then
   rustup toolchain install $RUST_VERSION
   TOOLCHAIN="+${RUST_VERSION}"
+
+  # The MSRV resolver does not properly select an MSRV-compliant version
+  # for this transient dependency.
+  cargo add [email protected]
+
   CARGO_RESOLVER_INCOMPATIBLE_RUST_VERSIONS=fallback cargo +nightly -Zmsrv-policy generate-lockfile
 fi