Migrate from Java 11 to Java 17

[devin-ai-integration]

Migrate from Java 11 to Java 17

Summary

This PR migrates the Spring Boot RealWorld application from Java 11 to Java 17. The changes update the Java version configuration in three locations:

1. build.gradle: Updated sourceCompatibility and targetCompatibility from '11' to '17'
2. .github/workflows/gradle.yml: Updated GitHub Actions CI workflow to use JDK 17
3. README.md: Updated documentation to reflect Java 17 requirement

All 68 tests pass successfully with Java 17, and the application compiles without errors.

Review & Testing Checklist for Human

• Verify CI passes completely
• Test the application locally with Java 17 installed (./gradlew bootRun and visit http://localhost:8080/tags)
• Consider if there are any Java 17-specific features or improvements you'd like to leverage in future work

Notes

• Spring Boot 2.6.3 is compatible with Java 17, so no framework updates were necessary
• No code changes were required - only version configuration updates
• Local testing confirmed all compilation and unit tests pass

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Link to Devin run: https://app.devin.ai/sessions/ed5eca39a25b4bf990ba7df4deb9ff2c
Requested by: @SachetCognition

[devin-ai-integration]

Original prompt from sachet.agarwal

# Migrate Spring Boot RealWorld Application from Java 11 to Java 17

## Context
This repository is a Spring Boot + MyBatis implementation of the RealWorld example application. It currently uses:
- **Spring Boot version**: 2.6.3
- **Current Java version**: 11
- **Application version**: 0.0.1-SNAPSHOT

## Task
Migrate the application from Java 11 to Java 17.

## Files to Modify

### 1. `build.gradle`
This file currently specifies Java 11 as the source and target compatibility. You need to update the Java version configuration in this file to use Java 17 instead.

The current configuration is located around lines 9-10 of `build.gradle` where the Java version is set to 11.

## Requirements
- Update all Java version references from 11 to 17
- Ensure the build configuration properly targets Java 17
- The application uses Spring Boot 2.6.3, which is compatible with Java 17

## Note
Make sure to update both the source and target compatibility settings to Java 17 in the Gradle build configuration.

You only need to look in the following repo: SachetCognition/spring-boot-realworld-example-app

[devin-ai-integration]

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