Change GitHub workflow

Run only if Dockerfile or any file related is changed.
Do not automatically run if notebooks' content is updated, since that
update can be easily pulled via git.

Author: edoardob90

.github/workflows/docker-build.yml

@@ -5,20 +5,24 @@ on:
   push:
     branches:
       - main
-    paths-ignore:
-      - "*.md"
-      - slides/**
-      - images/**
-      - .gitignore
+    paths:
+      - "Dockerfile"
+      - "docker/**"
+      - "binder/**"
+      - "**/environment.yml"
+      - "tutorial/tests/testsuite/**"
+      - ".github/workflows/docker-build.yml"
     tags:
       - "v*.*"
       - "v*.*.*"
   pull_request:
-    paths-ignore:
-      - "*.md"
-      - slides/**
-      - images/**
-      - .gitignore
+    paths:
+      - "Dockerfile"
+      - "docker/**"
+      - "binder/**"
+      - "**/environment.yml"
+      - "tutorial/tests/testsuite/**"
+      - ".github/workflows/docker-build.yml"
   workflow_dispatch:
 
 jobs: