dependabot: ignore Spring 6 as it requires Java 17

see https://github.com/KorAP/Kustvakt/issues/380#issuecomment-1314411796, see https://github.com/KorAP/Kustvakt/issues/380#issuecomment-1314411796

Change-Id: I0e035b93947d9722ae3a1f52915748a94253acc4
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 799212b..35a218e 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -29,6 +29,10 @@
       - dependency-name: "com.github.gwenn:sqlite-dialect"
         versions:
           - "> 0.1.0"
+      # Spring 6 and Jersey 3.1 require Java >= 17
+      - dependency-name: "org.springframework*"
+        versions:
+          - ">=6"
       - dependency-name: "org.glassfish.jersey.*"
         versions:
           - ">=3"