Move tox requirements into separate files

Author: dflook

.github/workflows/test.yaml

@@ -32,7 +32,9 @@ jobs:
         with:
           image: danielflook/python-minifier-build:${{ matrix.python }}-2025-09-26
           run: |
-            tox -r -e $(echo "${{ matrix.python }}" | tr -d .)
+            tox -r -e $(echo "${{ matrix.python }}" | tr -d .) -- --collect-only
+            rm -rf src
+            tox -e $(echo "${{ matrix.python }}" | tr -d .)
 
   test-windows:
     name: Test Windows