chore(ci): add dummy check for all checks passing (#298)

this job can be used to gate merging branches, rather than requiring the
individual checks in the GitHub branch protection UI. this allows us to
declare which jobs gate merging in this file, rather than out of band in
the UI.

.github/workflows/ci.yml

@@ -35,6 +35,26 @@ env:
   RUST_BACKTRACE: short
 
 jobs:
+  # dummy job to indicate everything has passed.
+  #
+  # this is used to gate merging branches, rather than requiring the individual
+  # checks in the GitHub branch protection UI. this allows us to declare which
+  # jobs gate merging in this file, rather than out of band in the UI.
+  all_systems_go:
+    name: "all systems go!"
+    runs-on: ubuntu-latest
+    needs:
+    - check
+    - clippy
+    - build-bins
+    - test
+    - test-host-miri
+    - docs
+    - rustfmt
+    - netlify_dryrun
+    steps:
+    - run: exit 0
+
   # run `just check`
   check:
     name: just check