dependabot: use correct values 'docker' and 'npm'

.github/dependabot.yml

@@ -9,7 +9,7 @@ updates:
   open-pull-requests-limit: 99
   labels:
   - dependencies
-- package-ecosystem: Docker
+- package-ecosystem: docker
   directories:
     - "/"
     - "/docker"
@@ -17,7 +17,7 @@ updates:
     interval: daily
   labels:
   - dependencies
-- package-ecosystem: yarn
+- package-ecosystem: npm
   directory: "/"
   schedule:
     interval: daily