Revert "fix: update runner configuration to use arc-runners-small"

This reverts commit f20e7d9

Author: polischuks

.github/workflows/auto-author-assign.yml

@@ -9,7 +9,7 @@ permissions:
 
 jobs:
   assign-author:
-    runs-on: arc-runners-small
+    runs-on: [self-hosted, small]
     timeout-minutes: 30
     if: ${{ !github.event.pull_request.assignee }}
     steps:

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ concurrency:
 jobs:
   lint:
     name: Lint with ruff
-    runs-on: arc-runners-small
+    runs-on: [ self-hosted, small ]
     timeout-minutes: 30
     steps:
       - uses: actions/checkout@v4
@@ -27,7 +27,7 @@ jobs:
 
   mypy:
     name: Static Type Checking
-    runs-on: arc-runners-small
+    runs-on: [ self-hosted, small ]
     timeout-minutes: 30
     steps:
       - uses: actions/checkout@v4
@@ -46,11 +46,11 @@ jobs:
       matrix:
         include:
           # Self-hosted runner
-          - os: arc-runners-small
+          - os: [ self-hosted, small ]
             python-version: "3.10"
-          - os: arc-runners-small
+          - os: [ self-hosted, small ]
             python-version: "3.11"
-          - os: arc-runners-small
+          - os: [ self-hosted, small ]
             python-version: "3.12"
 
           # Windows