ci(check-whitespace): stop requiring a read/write token

As part of some recent security tightening, GitHub introduced the
ability to configure GitHub workflows to be run with a read-only token.
This is much more secure, in particular when working in a public
repository: While the regular read/write token might be restricted to
writing to the current branch, it is not necessarily restricted to
access only the current Pull Request.

However, the `check-whitespace` workflow threw a wrench into this plan:
it _requires_ write access (because it wants to add a PR comment in case
of a whitespace issue).

Let's just skip that PR comment. The user can always click through to
the actual error, even if it is slightly less convenient.

Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: dscho

.github/workflows/check-whitespace.yml

@@ -51,21 +51,5 @@ jobs:
 
         if test -n "${log}"
         then
-          echo "::set-output name=checkout::"${log}""
           exit 2
         fi
-
-    - name: Add Check Output as Comment
-      uses: actions/github-script@v3
-      id: add-comment
-      env:
-        log: ${{ steps.check_out.outputs.checkout }}
-      with:
-        script: |
-            await github.issues.createComment({
-              issue_number: context.issue.number,
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              body: `Whitespace errors found in workflow ${{ github.workflow }}:\n\n\`\`\`\n${process.env.log.replace(/\\n/g, "\n")}\n\`\`\``
-            })
-      if: ${{ failure() }}