Added CLA Github action

.github/workflows/main.yml

@@ -0,0 +1,28 @@
+# This is a basic workflow to help you get started with Actions
+
+name: "CLA Assistant"
+on:
+  issue_comment:
+    types: [created]
+  pull_request_target:
+    types: [opened,closed,synchronize]
+
+jobs:
+  CLAssistant:
+    runs-on: ubuntu-latest
+    steps:
+      - name: "CLA Assistant"
+        if: (github.event.comment.body == 'recheck' || github.event.comment.body == 'I have read the CLA Document and I hereby sign the CLA') || github.event_name == 'pull_request_target'
+        # Alpha Release
+        uses: cla-assistant/github-action@v2.1.1-beta
+        env: 
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          # the below token should have repo scope and must be manually added by you in the repository's secret
+          PERSONAL_ACCESS_TOKEN : ${{ secrets.PERSONAL_ACCESS_TOKEN }}
+        with:
+          path-to-signatures: 'cla/cla.json'
+          path-to-cla-document: 'https://github.com/OPSILab/Idra/blob/master/idra-individual-cla.pdf' # e.g. a CLA or a DCO document
+          # branch should not be protected
+          branch: 'master'
+          allowlist: OPSILab,robcalla,emastrosimone,martinomaggio,sirnino,francescadag,dependabot,bot*
+          signed-commit-message: '$contributorName has signed the CLA in #$pullRequestNo'