Update dependabot config and git user settings

- Reduce open pull requests limit from 10 to 5
- Replace "rust" label with "bot" for consistency
- Add "bot" label to github-actions updates
- Change git commit author from github-actions to nerjs

Author: nerjs

.github/dependabot.yml

@@ -6,12 +6,12 @@ updates:
       interval: weekly
       time: "06:00"
     target-branch: dependencies
-    open-pull-requests-limit: 10
+    open-pull-requests-limit: 5
     assignees:
       - nerjs
     labels:
       - dependencies
-      - rust
+      - bot
     groups:
       rust-minor-patch:
         update-types:
@@ -29,6 +29,7 @@ updates:
       - nerjs
     labels:
       - dependencies
+      - bot
       - github-actions
     groups:
       gha-minor-patch:

.github/workflows/sync-dependencies.yml

@@ -24,8 +24,8 @@ jobs:
 
       - name: Configure git
         run: |
-          git config user.name "github-actions[bot]"
-          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git config user.name "nerjs"
+          git config user.email "nerjs.stap@gmail.com"
 
       - name: Sync or prepare deps-sync
         id: sync