remove buildpr

.github/workflows/pxt-buildpr.yml

@@ -1,31 +0,0 @@
-name: pxt-buildpr
-
-on: [pull_request]
-
-jobs:
-  build:
-
-    runs-on: ubuntu-latest
-
-    strategy:
-      matrix:
-        node-version: [8.x]
-
-    steps:
-      - uses: actions/checkout@v1
-      - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v1
-        with:
-          node-version: ${{ matrix.node-version }}
-      - name: npm install
-        run: |
-          sudo apt-get install xvfb
-          sudo npm install -g pxt
-          npm install
-      - name: pxt ci
-        run: |
-          pxt ci
-        env:
-          CHROME_BIN: chromium-browser
-          DISPLAY: :99.0
-          CI: true