chore(ci): rework when we run our workflows

Run workflows for pull requests and for pushes to main. We previously
only ran it for pushes, which works fine for contributors who have
direct repository access, but not when you contribute from a fork.

As a side effect we no longer run CI for non-main branches in the
repository.

Signed-off-by: Christoph Steiger <christoph.steiger@siemens.com>

Author: Urist-McGit

.github/workflows/containers.yml

@@ -5,6 +5,9 @@ name: Containers
 
 on:
   push:
+    branches:
+    - main
+  pull_request:
 
 jobs:
   build_containers:

.github/workflows/docs.yml

@@ -6,6 +6,9 @@ name: Docs
 
 on:
   push:
+    branches:
+    - main
+  pull_request:
 
 jobs:
   docs:

.github/workflows/lint.yml

@@ -6,6 +6,9 @@ name: Lint Python Code
 
 on:
   push:
+    branches:
+    - main
+  pull_request:
 
 jobs:
   format:

.github/workflows/test.yml

@@ -6,6 +6,9 @@ name: Tests
 
 on:
   push:
+    branches:
+    - main
+  pull_request:
 
 jobs:
   test: