build: remove freebsd and openbsd buildbots (#3974)

The buildbots are super flaky compared to other platforms and no one
seems invested enough to investigate. They don't add nearly enough value
for the friction they cause so away they go.

Fixes: https://github.com/libuv/libuv/issues/3934
Fixes: https://github.com/libuv/libuv/issues/3972
Refs: https://github.com/libuv/libuv/pull/3548

.github/workflows/CI-unix.yml

@@ -146,36 +146,3 @@ jobs:
       - name: Test
         run: |
           ${{ matrix.config.qemu }} build/uv_run_tests_a
-
-  build-bsd:
-    timeout-minutes: 30
-    runs-on: ${{ matrix.config.runner }}
-    name: build-${{ matrix.config.os }}-${{ matrix.config.version }}
-
-    strategy:
-      fail-fast: false
-      matrix:
-        config:
-          # The OS versions supported are specific to the version of the action
-          # https://github.com/cross-platform-actions/action/blob/master/changelog.md
-          - { os: freebsd, version: '13.1', runner: 'ubuntu-latest', install: 'pkg install -y' }
-          - { os: openbsd, version: '7.2',  runner: 'macos-11', install: 'pkg_add -I' }
-
-    steps:
-      - uses: actions/checkout@v2
-
-      - uses: cross-platform-actions/action@v0.9.0
-        with:
-          operating_system: ${{ matrix.config.os }}
-          version: ${{ matrix.config.version }}
-          run: |
-            sudo ${{ matrix.config.install }} cmake ninja
-            sudo hostname -s ci-host
-            mkdir build
-            cd build
-            cmake .. -DBUILD_TESTING=ON -G Ninja
-            cmake --build .
-            ls -lh
-            ./uv_run_tests platform_output
-            ./uv_run_tests_a platform_output
-            ctest -V