fix: duplicate workflows in push and pull_request

.github/workflows/fmt.yml

@@ -1,7 +1,9 @@
 name: Check Formatting
 on:
+  push:
+    branches:
+      - main
   - pull_request
-  - push
 jobs:
   check:
     name: Check Formatting

.github/workflows/spawn_examples.yml

@@ -1,7 +1,9 @@
 name: Spawn Examples
 on:
+  push:
+    branches:
+      - main
   - workflow_dispatch
-  - push
   - pull_request
 jobs:
   generate_example_paths:

.github/workflows/spellcheck.yml

@@ -1,7 +1,9 @@
 name: Spellcheck
 on:
+  push:
+    branches:
+      - main
   - pull_request
-  - push
 jobs:
   spellcheck:
     runs-on: ubuntu-latest

.github/workflows/test.yml

@@ -1,7 +1,9 @@
 name: Test
 on:
+  push:
+    branches:
+      - main
   - pull_request
-  - push
 jobs:
   test:
     name: Run Tests