Add github-copilot[bot] to CLA allowlist

Included github-copilot[bot] in the allowlist for CLA workflow to permit automated contributions from this bot without requiring CLA signature.

Author: stesee

.github/workflows/cla.yml

@@ -21,7 +21,7 @@ jobs:
           path-to-document: 'https://github.com/Codeuctivity/SkiaSharp.Compare/blob/main/cla.md' # e.g. a CLA or a DCO document
           # branch should not be protected
           branch: 'cla'
-          allowlist: dependabot[bot],stesee
+          allowlist: dependabot[bot],stesee,github-copilot[bot]
 
          #below are the optional inputs - If the optional inputs are not given, then default values will be taken
          #remote-organization-name: enter the remote organization name where the signatures should be stored (Default is storing the signatures in the same repository)