CI: prevent Windows 2019 cache reuse on Windows 2022

Author: g-andrade

.github/workflows/ci.yml

@@ -60,7 +60,7 @@ jobs:
         run: |
           # https://github.com/actions/runner-images/issues/5251#issuecomment-1071030822
           echo "prev_github_run_number=$(${{github.run_number}} - 1)" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
-          echo "build_cache_prefix=_build-cache2-for-os-${{runner.os}}-otp-${{matrix.otp_vsn}}-rebar3-${{steps.setup-beam.outputs.rebar3-version}}" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+          echo "build_cache_prefix=_build-cache2-for-os-${{runner.os}}B-otp-${{matrix.otp_vsn}}-rebar3-${{steps.setup-beam.outputs.rebar3-version}}" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
 
       - name: "Windows: set dynamic env (2)"
         if: ${{runner.os == 'Windows'}}