fix(dependabot): use valid Docker version requirement

Author: dantte-lp

.github/dependabot.yml

@@ -28,9 +28,7 @@ updates:
     ignore:
       - dependency-name: library/python
         versions:
-          - "*a*"
-          - "*b*"
-          - "*rc*"
+          - 3.15.0b3
   - package-ecosystem: github-actions
     directory: /
     schedule: