chore: run the CI even for PR not targetting master (and remove doc build twice) (#2504)

Replaces #2493

.github/workflows/test-docs.yml

@@ -4,7 +4,9 @@ on:
   push:
     branches: [master]
   pull_request:
-    branches: [master]
+    path:
+      - umap/*
+      - pyproject.toml
 
 jobs:
   tests:
@@ -61,7 +63,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: '3.11'
+          python-version: '3.12'
       - name: Install dependencies
         run: |
           python3 -m pip install -e .[test,dev]
@@ -72,18 +74,3 @@ jobs:
 
       - name: Run Docs
         run: make docs
-
-  docs:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - name: Set up Python
-        uses: actions/setup-python@v5
-        with:
-          python-version: '3.11'
-      - name: Install dependencies
-        run: |
-          python3 -m pip install -r docs/requirements.txt
-
-      - name: Run Docs
-        run: mkdocs build