dependabot: ignore major an minor semver updates for docker images (#286)

* dependabot: ignore major an minor semver updates for docker images

* Add required dependency-name

Author: xrmx

.github/dependabot.yml

@@ -43,3 +43,6 @@ updates:
     registries: "*"
     schedule:
       interval: "daily"
+    ignore:
+      - dependency-name: "python*"
+        update-types: ["version-update:semver-major", "version-update:semver-minor"]