Correct Bash syntax

Author: pcolby

.github/workflows/build.yaml

@@ -488,7 +488,7 @@ jobs:
     steps:
       - if: matrix.toolchain != 'msvc'
         shell: bash
-        run: tee -a '$GITHUB_PATH" <<< 'C:\msys64\mingw64\bin'
+        run: tee -a "$GITHUB_PATH" <<< 'C:\msys64\mingw64\bin'
       - name: Install LCOV
         if: matrix.toolchain != 'msvc'
         run: pacman --sync --noconfirm --verbose mingw-w64-x86_64-lcov