Ensure dependabot only pulls stable python docker

Author: Themitchell

.github/dependabot.yaml

@@ -6,6 +6,13 @@ updates:
     directory: "/"
     schedule:
       interval: "daily"
+    ignore:
+      - dependency-name: "python"
+        versions:
+          - "*.dev*-slim*"
+          - "*[0-9]a[0-9]*-slim*"
+          - "*[0-9]b[0-9]*-slim*"
+          - "*[0-9]rc[0-9]*-slim*"
     cooldown:
       default-days: 7