Upgrade Gradle to 8.14 in CI Workflows and Gradle Wrapper (#3425)

# Description of Changes

This pull request upgrades the Gradle build system from version 8.12 to
8.14 across the Stirling-PDF project to enhance build stability,
compatibility, and performance. The changes include:

- **What was changed**:
- Updated the Gradle wrapper version in
`gradle/wrapper/gradle-wrapper.properties` from `8.12` to `8.14`.
- Modified the `tasks.wrapper` configuration in `build.gradle` to
specify `gradleVersion = "8.14"`.
- Updated Gradle version references in GitHub Actions workflows
(`multiOSReleases.yml`, `push-docker.yml`, `releaseArtifacts.yml`) from
`8.12` to `8.14` to ensure consistent CI/CD builds.

- **Why the change was made**:
- Gradle 8.14 includes bug fixes, performance improvements, and enhanced
compatibility with newer JDK versions (e.g., Java 17 and 21, as
supported by Stirling-PDF).
- Ensures alignment with the latest Gradle features and security
patches, reducing potential build issues in development and CI/CD
environments.
- Supports the project's recommendation to use newer JDK versions (e.g.,
Java 21) and improves integration with the Foojay Toolchains Plugin.

- **Challenges encountered**:
- Verified compatibility of Gradle 8.14 with existing plugins (e.g.,
`org.springframework.boot`, `org.sonarqube`, `com.diffplug.spotless`) to
ensure no breaking changes.
- Tested CI/CD workflows to confirm that the updated Gradle version does
not introduce failures in build, test, or deployment pipelines.
- Ensured the Gradle wrapper distribution URL is correctly updated to
avoid download issues.


---

## Checklist

### General

- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [x] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md)
(if applicable)
- [x] I have performed a self-review of my own code
- [x] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [x] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#6-testing)
for more details.

gradlew

@@ -114,7 +114,7 @@ case "$( uname )" in                #(
   NONSTOP* )        nonstop=true ;;
 esac
 
-CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+CLASSPATH="\\\"\\\""
 
 
 # Determine the Java command to use to start the JVM.
@@ -205,7 +205,7 @@ fi
 DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 
 # Collect all arguments for the java command:
-#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
 #     and any embedded shellness will be escaped.
 #   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
 #     treated as '${Hostname}' itself on the command line.
@@ -213,7 +213,7 @@ DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
         -classpath "$CLASSPATH" \
-        org.gradle.wrapper.GradleWrapperMain \
+        -jar "$APP_HOME/gradle/wrapper/gradle-wrapper.jar" \
         "$@"
 
 # Stop when "xargs" is not available.