.github/workflows/cygwin.yml: Removed

There is no active maintainer for cygwin.  The CI failure is too noisy.

[Misc #16407]

.github/workflows/cygwin.yml

@@ -1,93 +0,0 @@
-name: Cygwin
-on:
-  push:
-    branches:
-      - '*'
-  pull_request:
-    branches:
-      - '*'
-jobs:
-  make:
-    strategy:
-      matrix:
-        test_task: [test]
-        os: [windows-2019]
-        vs: [2019]
-      fail-fast: false
-    runs-on: ${{ matrix.os }}
-    if: "!contains(github.event.head_commit.message, '[ci skip]')"
-    steps:
-      - uses: actions/cache@v1
-        with:
-          path: C:\Users\runneradmin\AppData\Local\Temp\chocolatey
-          key: ${{ runner.os }}-cygwin-chocolatey-${{ matrix.os }}-${{ github.sha }}
-          restore-keys: |
-            ${{ runner.os }}-cygwin-chocolatey-${{ matrix.os }}-
-            ${{ runner.os }}-cygwin-chocolatey-
-      - name: Install cygwin base packages with chocolatey
-        run: |
-          choco install --no-progress cygwin
-      - uses: actions/cache@v1
-        with:
-          path: C:\tools\cygwin\package
-          key: ${{ runner.os }}-cygwin-package-${{ matrix.os }}-${{ github.sha }}
-          restore-keys: |
-            ${{ runner.os }}-cygwin-package-${{ matrix.os }}-
-            ${{ runner.os }}-cygwin-package-
-      - name: Install cygwin additional packages
-        run: |
-          C:\tools\cygwin\cygwinsetup.exe -qgnNdO -R C:/tools/cygwin -l C:/tools/cygwin/package -s http://mirrors.kernel.org/sourceware/cygwin/ -P autoconf,bison,gcc-core,git,libffi-devel,libgdbm-devel,libgmp-devel,libreadline-devel,libssl-devel,make,patch,ruby,zlib-devel
-        shell: cmd
-      - name: Set ENV
-        run: |
-          echo '::set-env name=PATH::C:\tools\cygwin\bin;C:\tools\cygwin\usr\bin'
-      # Not using official actions/checkout because it's unstable and sometimes doesn't work for a fork.
-      - name: Checkout ruby
-        run: |
-          git clone --single-branch --shallow-since=yesterday --branch=%GITHUB_REF:refs/heads/=% https://github.com/${{ github.repository }} src
-          git -C src reset --hard ${{ github.sha }}
-        if: github.event_name == 'push'
-        shell: cmd
-      - name: Checkout a pull request
-        run: |
-          git clone --single-branch --shallow-since=yesterday --branch=${{ github.event.pull_request.head.ref }} https://github.com/${{ github.event.pull_request.head.repo.full_name }} src
-          git -C src reset --hard ${{ github.event.pull_request.head.sha }}
-        if: github.event_name == 'pull_request'
-        shell: cmd
-      - run: ./src/tool/actions-commit-info.sh
-        shell: bash
-        id: commit_info
-      - name: Autoconf
-        run: |
-          cd src
-          bash /usr/bin/autoconf
-        shell: cmd
-      - name: Configure
-        run: |
-          md build
-          cd build
-          bash ../src/configure
-        shell: cmd
-      - name: make
-        run: |
-          make -C build
-        shell: cmd
-      # TODO: Fix test fail on cygwin environment on GitHub Actions
-      # - name: make btest
-      #   run: |
-      #     make -C build btest
-      #   shell: cmd
-      - uses: k0kubun/action-slack@v2.0.0
-        with:
-          payload: |
-            {
-              "attachments": [{
-                "text": "${{ github.workflow }} / ${{ matrix.test_task }} <https://github.com/${{ github.repository }}/commit/${{ github.sha }}/checks|${{ steps.commit_info.outputs.COMMIT_DATE }} #${{ steps.commit_info.outputs.COMMIT_NUMBER_OF_DAY }}> " +
-                        "(<https://github.com/${{ github.repository }}/commit/${{ github.sha }}|" + "${{ github.sha }}".substring(0, 10) + ">) " +
-                        "of ${{ github.repository }}@" + "${{ github.ref }}".split('/').reverse()[0] + " by ${{ github.event.head_commit.committer.name }} failed",
-                "color": "danger"
-              }]
-            }
-        env:
-          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}
-        if: failure() && github.event_name == 'push'