ci: Fixed typo in temp directory variable name

.github/workflows/test.yml

@@ -47,7 +47,7 @@ jobs:
       - name: Ensure TMPDIR is valid for MacOS
         if: runner.os == 'macOS'
         run: |
-          echo "TMPDIR={{ runner.temp }}" >> $GITHUB_ENV
+          echo "TMPDIR=${{ runner.temp }}" >> $GITHUB_ENV
 
       - name: Install Rust stable
         uses: dtolnay/rust-toolchain@stable