Enable BC workflow (#169)

Author: rustamwin

.github/workflows/bc.yml

@@ -0,0 +1,15 @@
+on:
+  - pull_request
+  - push
+
+name: backwards compatibility
+jobs:
+  roave_bc_check:
+    name: Roave BC Check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - name: fetch tags
+        run: git fetch --depth=1 origin +refs/tags/*:refs/tags/*
+      - name: Roave BC Check
+        uses: docker://nyholm/roave-bc-check-ga