WIP: attempt to fix test workflows

.github/workflows/run-tests.yml

@@ -96,6 +96,11 @@ jobs:
         echo "$(pwd -W)/USD_INSTALL/lib" >> $GITHUB_PATH
         echo "$(pwd -W)/USD_INSTALL/bin" >> $GITHUB_PATH
 
+    - name: Set up Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: '3.9'
+
     - name: Fetch example glTF file
       run: mkdir test && curl "https://github.com/KhronosGroup/glTF-Sample-Models/raw/db9ff67c1116cfe28eb36320916bccd8c4127cc1/2.0/ToyCar/glTF-Binary/ToyCar.glb" -L -v -o test/asset.glb
 
@@ -145,10 +150,6 @@ jobs:
         sudo apt upgrade
         sudo apt-get install mesa-utils xvfb qt5-default
 
-      # usdrecord needs python (may change soon!)
-    - name: Install Python packages
-      run: pip3 install --user PySide2 PyOpenGL
-
     - name: Set up environment variables
       run: |
         # Test options
@@ -173,6 +174,15 @@ jobs:
         # guc debug output
         echo "TF_DEBUG=GUC" >> $GITHUB_ENV
 
+    - name: Set up Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: '3.9'
+
+      # usdrecord needs python (may change soon!)
+    - name: Install Python packages
+      run: pip3 install --user PySide2 PyOpenGL
+
     - name: Start virtual framebuffer
       run: |
         Xvfb :1 -screen 0 1280x960x24 &