Fix Swagger annotation warnings in geode-dunit compilation (#7948)

Add io.swagger.core.v3:swagger-annotations dependency to geode-dunit's
compile classpath to resolve compilation warnings about missing
AccessMode enum constant.

Problem:
The geode-dunit module's compilation was generating warnings:
  warning: unknown enum constant AccessMode.READ_ONLY
  reason: class file for io.swagger.v3.oas.annotations.media.Schema$AccessMode
  not found

Root Cause:
The geode-dunit code references Swagger/OpenAPI annotations (such as
@Schema with AccessMode) through transitive dependencies from geode-core
and geode-gfsh, both of which have swagger-annotations as implementation
dependencies. However, the Swagger annotations API was not explicitly
declared as a compile-time dependency for geode-dunit. This caused the
Java annotation processor to be unable to resolve the AccessMode enum
during compilation.

Solution:
Added 'io.swagger.core.v3:swagger-annotations' to compileOnly
configuration in geode-dunit/build.gradle. This ensures the Swagger
annotations API is available during compilation, allowing the annotation
processor to properly resolve Swagger/OpenAPI annotations.

The compileOnly scope is appropriate here since:
- Swagger annotations API is only needed at compile time for annotation
  processing
- Runtime implementation is provided by transitive dependencies from
  geode-core and geode-gfsh
- Keeps the classpath minimal and avoids duplicate dependencies
- Consistent with patterns in geode-management and geode-deployment-legacy

Testing:
Verified with: ./gradlew :geode-dunit:compileJava
Build completes successfully without Swagger annotation warnings.

Related modules using similar pattern:
- geode-core: has swagger-annotations in implementation scope
- geode-gfsh: has swagger-annotations in implementation scope
- geode-management: has swagger-annotations in testCompileOnly scope
- geode-deployment-legacy: has swagger-annotations in compileOnly scope
- geode-assembly: has swagger-annotations in various test scopes

Author: JinwooHwang

geode-dunit/build.gradle

@@ -22,6 +22,7 @@ plugins {
 
 dependencies {
   api(platform(project(':boms:geode-all-bom')))
+  compileOnly('io.swagger.core.v3:swagger-annotations')
   implementation(project(':geode-logging'))
   implementation(project(':geode-serialization'))
   implementation(project(':geode-membership'))