Fix RUST_LATEST_STABLE_VERSION

Author: minikin

.github/workflows/ci_tests.yml

@@ -16,7 +16,7 @@ on:
        - 'Makefiles/**'
 
 env:
-  RUST_LATEST_STABLE_VERSION: 1.65
+  RUST_LATEST_STABLE_VERSION: '1.65'
   CARGO_TERM_COLOR: always
   RUSTFLAGS: -D warnings
   RUST_BACKTRACE: 1
@@ -43,7 +43,7 @@ jobs:
       - name: Run vit-ss tests
         uses: actions-rs/toolchain@v1
         with:
-          toolchain: $$RUST_LATEST_STABLE_VERSION
+          toolchain: $RUST_LATEST_STABLE_VERSION
       - run: |
           cargo build -p vit-servicing-station-cli -p vit-servicing-station-server
           cargo nextest run \