chore: configure CI for 1.x branch (#1528)

Author: shobsi

.github/workflows/docs.yml

@@ -1,7 +1,7 @@
 on:
   pull_request:
     branches:
-      - main
+      - v1
 name: docs
 jobs:
   docs:

.github/workflows/lint.yml

@@ -1,7 +1,7 @@
 on:
   pull_request:
     branches:
-      - main
+      - v1
 name: lint
 jobs:
   lint:

.github/workflows/mypy.yml

@@ -1,7 +1,7 @@
 on:
   pull_request:
     branches:
-      - main
+      - v1
 name: mypy
 jobs:
   mypy:

.github/workflows/unittest.yml

@@ -1,7 +1,7 @@
 on:
   pull_request:
     branches:
-      - main
+      - v1
 name: unittest
 jobs:
   unit: