update bot match for gitlab default CM

Author: vim-zz

docs/downloads/gitStream-gl.cm

@@ -10,15 +10,15 @@ automations:
   linearb_ai_review:
     if:
       - {{ not pr.draft }}
-      - {{ pr.author | match(list=['github-actions', 'dependabot', '[bot]']) | nope }}
+      - {{ IS_NOT_A_BOT }}
     run:
       - action: code-review@v1
 
   # Use LinearB's AI service to add a description to the PR
   linearb_ai_description:
     if:
       - {{ not pr.draft }}
-      - {{ pr.author | match(list=['github-actions', 'dependabot', '[bot]']) | nope }}
+      - {{ IS_NOT_A_BOT }}
     run:
       - action: describe-changes@v1
         args:
@@ -73,3 +73,5 @@ colors:
   red: 'b60205'
   yellow: 'fbca04'
   green: '0e8a16'
+
+IS_NOT_A_BOT: {{ pr.author | match(list=['_bot_', '[bot]', 'dependabot']) | nope }}