Fix quotes

Author: andrjohns

.github/workflows/main.yml

@@ -92,8 +92,8 @@ jobs:
     - name: Download and install Rtools45
       if: runner.os == 'Windows'
       run: |
-        $ARCH = if (${{ matrix.os }} == 'windows-11-arm') { 'aarch64' } else { 'x86_64' }
-        $RTOOLS = if (${{ matrix.os }} == 'windows-11-arm') { 'rtools45-$ARCH' } else { 'rtools45' }
+        $ARCH = if ('${{ matrix.os }}' == 'windows-11-arm') { 'aarch64' } else { 'x86_64' }
+        $RTOOLS = if ('${{ matrix.os }}' == 'windows-11-arm') { 'rtools45-$ARCH' } else { 'rtools45' }
         Invoke-WebRequest -Uri https://github.com/r-hub/rtools45/releases/download/latest/$RTOOLS.exe -OutFile $RTOOLS.exe
         Start-Process -FilePath $RTOOLS.exe -ArgumentList "/install /norestart /verysilent /SUPPRESSMSGBOXES" -NoNewWindow -Wait
         echo "C:/$RTOOLS/usr/bin;C:/$RTOOLS/$ARCH-w64-mingw32.static.posix/bin" | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8