Improve GitHub workflows

- modify triggering events: only push to main branch and pull_requests trigger lint
- add pylint to the linting workflow

.github/workflows/docs.yml

@@ -2,7 +2,8 @@ name: Docs
 
 on:
   push:
-    branches: [ "main" ]
+    branches: 
+      - main
 
 jobs:
   build_docs:

.github/workflows/lint.yml

@@ -1,9 +1,14 @@
 name: Lint
 
-on: [push]
+on: 
+  pull_request
+  push: 
+    branches: 
+      - main  
 
 jobs:
-  build:
+  lint:
+    name: Lint (black + pylint)
     runs-on: ubuntu-latest
     strategy:
       matrix:
@@ -17,7 +22,11 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install black
-    - name: Analysing the code with black
+        pip install black pylint
+    - name: Analyse the code with black
       run: |
         black src --check
+    - name: Analyse the code with pylint
+    # ignore grid tables when checking for long lines 
+      run: |
+        pylint src --ignored-modules rdkit --ignore-long-lines "^\s*(\+[\-\=]+)+\+|(?:\|.*)+\|"