github: Remove build on Ubuntu Xenial (16.04)

Support for it will be removed later this month.

.github/workflows/linux.yml

@@ -153,43 +153,3 @@ jobs:
           name: Logs ${{ github.job }}
           path: config.log
           retention-days: 5
-
-  xenial:
-    needs: pre-check
-    if: ${{ needs.pre-check.outputs.should_skip != 'true' }}
-    runs-on: ubuntu-16.04
-    strategy:
-      matrix:
-        test: [ all ]
-        compiler: [ gcc, clang ]
-        include:
-          - test: openssl-1.0
-          - test: openssl-1.0
-            leak-detective: yes
-    env:
-      LEAK_DETECTIVE: ${{ matrix.leak-detective || 'no' }}
-      CC: ${{ matrix.compiler || 'gcc' }}
-      TEST: ${{ matrix.test }}
-      # this is the default with newer versions and fixes builds with clang
-      CCACHE_CPP2: true
-    steps:
-      - uses: actions/checkout@v2
-      - uses: actions/cache@v2
-        with:
-          path: ~/.ccache
-          key: ccache-xenial-${{ env.CC }}-${{ matrix.test }}-${{ github.sha }}
-          restore-keys: |
-            ccache-xenial-${{ env.CC }}-${{ matrix.test }}-
-            ccache-xenial-${{ env.CC }}-
-      - run: |
-          sudo apt-get install -qq ccache
-          echo "PATH=/usr/lib/ccache:$PATH" >> $GITHUB_ENV
-          ccache -z
-      - uses: ./.github/actions/default
-      - run: ccache -s
-      - if: ${{ failure() }}
-        uses: actions/upload-artifact@v2
-        with:
-          name: Logs ${{ github.job }}
-          path: config.log
-          retention-days: 5