Update deprecated GitHub Actions and add Python versions (wireviz#408)

Running 6 different Python versions (3.7 to 3.12) in parallel now.
NOTE: This is in conflict with wireviz#309, but can be resolved easily in a later PR.

GitHub Actions require an update:
- actions/upload-artifact@v3 is scheduled for deprecation on November
30, 2024.
- Similarly, v1/v2 are scheduled for deprecation on June 30, 2024. 
- Updating this comes with a breaking change in upload-artifact@v4:

Uploading to the same named Artifact multiple times.

Due to how Artifacts are created in this new version, it is no longer
possible to upload to the same named Artifact multiple times. You must
either split the uploads into multiple Artifacts with different names,
or only upload once. Otherwise you will encounter an error.

The artifact .zip files therefore have the python version added to
their name.

.github/workflows/main.yml

@@ -4,29 +4,32 @@ on: [push, pull_request, workflow_dispatch]
 
 jobs:
   build:
-    runs-on: ubuntu-latest
     strategy:
-      max-parallel: 4
+      max-parallel: 6
       matrix:
-        python-version: [3.7, 3.8]
+        os: [ubuntu-latest]
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
+    runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v5
       with:
         python-version: ${{ matrix.python-version }}
     - name: Setup Graphviz
-      uses: ts-graphviz/setup-graphviz@v1
+      uses: ts-graphviz/setup-graphviz@v2
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
         pip install .
     - name: Create Examples
-      run: PYTHONPATH=$(pwd)/src:$PYTHONPATH cd src/wireviz/ && python build_examples.py
+      run: PYTHONPATH=$(pwd)/src/wireviz:$PYTHONPATH cd src/wireviz/ && python build_examples.py
     - name: Upload examples, demos, and tutorials
-      uses: actions/upload-artifact@v2
+      uses: actions/upload-artifact@v4
       with:
-        name: examples-and-tutorials
+        name: examples-and-tutorials-v${{ matrix.python-version }}
         path: |
           examples/
-          tutorial/
+          tutorial/
+        if-no-files-found: error
+