Trigger only actions in presence of label

Author: Radonirinaunimi

.github/workflows/regression.yml

@@ -1,22 +1,16 @@
 name: regression
 
 # start job only for PRs when a label is added.
-on: push
-  # pull_request:
-  #   types: [labeled]
+on:
+  pull_request:
+    types: [labeled]
 
 jobs:
   regresstion:
-    # if: contains(github.event.pull_request.labels.*.name, 'run-regression')
+    if: contains(github.event.pull_request.labels.*.name, 'run-regression')
     name: regression
     runs-on: pineko-stbc3
 
-    # container:
-    #   image: ghcr.io/nnpdf/lhapdf:v2
-    #   credentials:
-    #     username: ${{ github.repository_owner }}
-    #     password: ${{ github.token }}
-
     steps:
       - uses: actions/checkout@v2
         with: