chore(ci): add back build job

This is required by the repo in order to merge into master.
Original build job was removed when it was split by feature.
Has the same original semantics by dependending on the split jobs.

Author: Mirko-von-Leipzig

.github/workflows/ci.yml

@@ -130,6 +130,14 @@ jobs:
       - name: Test --features strict
         run: timeout 15m cargo test -p interledger-btp --features strict
 
+  build:
+    # Repo requires a `build` job to succeed in order to merge into master.
+    # A step and runs-on is required for a job to be valid.
+    needs: [interledger, interledger-packet, interledger-stream, interledger-btp]
+    runs-on: ubuntu-latest
+    steps:
+      - name: Success
+        run: echo "Success"
 
   settlement-engines:
     # This job builds the ethereum-settlement-engine required by `test-md`.