build: add CodeQL workflow

.github/workflows/codeql.yml

@@ -0,0 +1,50 @@
+# Copyright The ORAS Authors.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: "CodeQL"
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches: [ "main" ]
+  schedule:
+    - cron: '30 5 * * 6'
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+    strategy:
+      matrix:
+        go-version: ['1.19', '1.20']
+      fail-fast: false
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+      - name: Set up Go ${{ matrix.go-version }} environment
+        uses: actions/setup-go@v4
+        with:
+          go-version: ${{ matrix.go-version }}
+          check-latest: true
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v2
+        with:
+          languages: go
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@v2