remove imagemagick step + update python action

Author: jamie-mh

.github/workflows/main.yml

@@ -13,9 +13,9 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Set up Python
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v5
         with:
-          python-version: "3.11"
+          python-version: "3.12"
           cache: "pip"
 
       - name: Install pip packages
@@ -38,9 +38,6 @@ jobs:
       - name: Install oxipng
         run: which oxipng || cargo install oxipng
 
-      - name: Install ImageMagick
-        run: sudo apt-get install -y imagemagick
-
       - name: Build packs
         run: |
           for builder in build_*.py; do