Add CI check for up-to-date type generation (#225)

Add a CI check to ensure that the `types.go` file generated from
`schema.json` is up-to-date.

Types are generated from the `schema.json` file but there was no check
in place to ensure that the two were consistent.

This PR runs `make generate` to correct an inconsistency between the
definitions and the generated types and adds the check so that we can't
repeat this mistake.

An example failed run where the types are out of date is
[here](https://github.com/xataio/pgroll/actions/runs/7475710605/job/20344427261).

.github/workflows/build.yml

@@ -57,8 +57,26 @@ jobs:
           fi
         done
 
+  type-generation:
+    name: type generation
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Generate types
+        run: |
+          make generate
+
+      - name: Ensure generated types are up-to-date
+        run: |
+          if ! git diff --quiet; then
+            echo "generated types are out of date!"
+            echo "run 'make generate' to regenerate type definitions"
+            exit 1
+          fi
+
   license-check:
-    name: License check
+    name: license check
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
@@ -106,7 +124,7 @@ jobs:
 
   release:
     runs-on: ubuntu-latest
-    needs: [test, lint, examples, license-check]
+    needs: [test, lint, examples, license-check, type-generation]
     if: startsWith(github.ref, 'refs/tags/')
     env:
       DOCKER_CLI_EXPERIMENTAL: "enabled"