deps: pin seaweedfs/goexif at v1.0.3 and stop dependabot re-bumping it (#11648)

* deps: pin github.com/seaweedfs/goexif back to v1.0.3

The fork's newest tagged release is v1.0.3; the v2.0.0+incompatible
requirement resolved to older, untagged code and breaks isolated
builds that fetch it from the proxy.

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* ci: stop dependabot bumping seaweedfs/goexif past its latest tag

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* test/kafka: settle goexif at v1.0.3 too

The kafka test module recorded v2.0.0+incompatible in its own requires,
so MVS kept selecting it over the pinned v1.0.3 in the root module.

---------

Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

.github/dependabot.yml

@@ -10,3 +10,5 @@ updates:
   directory: "/"
   schedule:
     interval: weekly
+  ignore:
+    - dependency-name: "github.com/seaweedfs/goexif"