Drop GitHub Actions (we now have Concourse for PRs).

Signed-off-by: Matt Moyer <moyerm@vmware.com>

.github/workflows/pull-request-ci.yml

@@ -1,42 +0,0 @@
-name: CI
-on:
-  push:
-    tags:
-      - v*
-    branches:
-      - main
-  pull_request:
-
-jobs:
-  golangci:
-    name: Lint
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - name: golangci-lint
-        uses: golangci/golangci-lint-action@v1
-        with:
-          version: v1.28
-
-  build:
-    name: Build
-    runs-on: ubuntu-latest
-    steps:
-    - name: Set up Go 1.14
-      uses: actions/setup-go@v2
-      with:
-        go-version: ^1.14
-      id: go
-    - name: Checkout
-      uses: actions/checkout@v2
-    - name: Cache Dependencies
-      uses: actions/cache@v2
-      with:
-        path: ~/go/pkg/mod
-        key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
-        restore-keys: |
-          ${{ runner.os }}-go-
-    - name: Build
-      run: go build -v ./...
-    - name: Test
-      run: go test -cover ./...