add github action for coverity scan

.github/workflows/coverity-scan.yml

@@ -0,0 +1,54 @@
+# based on https://github.com/ruby/actions-coverity-scan/blob/282dd059/.github/workflows/coverity-scan.yml
+name: coverity-scan
+on:
+  schedule:
+    - cron: '0 18 * * *' # Daily at 18:00 UTC
+
+jobs:
+  latest:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Install libraries
+        run: |
+          set -x
+          sudo apt-get update
+          sudo apt-get install make pkgconf gcc libarchive-dev zlib1g-dev openssl-dev
+
+      - name: Checkout void-linux/xbps
+        run: |
+          git clone --depth=1 https://github.com/void-linux/xbps .
+
+      - name: Download Coverity Build Tool
+        run: |
+          wget -q https://scan.coverity.com/download/cxx/linux64 --post-data "token=$TOKEN&project=ruby" -O cov-analysis-linux64.tar.gz
+          mkdir cov-analysis-linux64
+          tar xzf cov-analysis-linux64.tar.gz --strip 1 -C cov-analysis-linux64
+        env:
+          TOKEN: ${{ secrets.COVERITY_SCAN_TOKEN }}
+
+      - name: Fixed world writable dirs
+        run: |
+          chmod go-w $HOME
+          sudo chmod -R go-w /usr/share
+
+      - name: Configure
+        run: ./configure
+
+      - name: Build with cov-build
+        run: |
+          export PATH=`pwd`/cov-analysis-linux64/bin:$PATH
+          cov-build --dir cov-int make
+
+      - name: Submit the result to Coverity Scan
+        run: |
+          tar czvf xbps.tgz cov-int
+          curl \
+            --form project=ruby \
+            --form token=$TOKEN \
+            --form email=github@voidlinux.org \
+            --form file=@xbps.tgz \
+            --form version=trunk \
+            --form description="" \
+            https://scan.coverity.com/builds?project=ruby
+        env:
+          TOKEN: ${{ secrets.COVERITY_SCAN_TOKEN }}