Update Java Server SDK version range to [7.0.0, 8.0.0)

[devin-ai-integration]

Summary

Updates the launchdarkly-java-server-sdk Gradle dependency range from [6.0.0, 7.0.0) to [7.0.0, 8.0.0). The previous range excluded all 7.x releases; the latest available version is 7.12.0.

This is a major version bump (6.x → 7.x) for the transitive SDK dependency. The app itself only uses the OpenFeature API surface (via launchdarkly-openfeature-serverprovider), so direct API breakage risk is low, but the provider's compatibility with SDK 7.x should be confirmed.

Review & Testing Checklist for Human

• Verify that launchdarkly-openfeature-serverprovider 1.x is compatible with launchdarkly-java-server-sdk 7.x (check the provider's own declared dependency range — if it already pulls in 7.x transitively, the explicit SDK dependency here may be redundant or conflicting)
• Build and run the example: ./gradlew shadowJar && LAUNCHDARKLY_SDK_KEY=<key> java -jar build/libs/*.jar — confirm it initializes and evaluates a flag
• Check that Gradle dependency resolution doesn't produce version conflicts between the provider's transitive SDK version and the explicitly declared [7.0.0, 8.0.0) range

Notes

• Not tested locally (no Java toolchain available in build environment). Relies on CI and human verification.
• Requested by: rlamb@launchdarkly.com
• Devin Session

[devin-ai-integration]

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