Build/CI: Modernize build.yml

[dsmiley]

• Test on more Java versions
• Remove travis.yml; unused

[Copilot]

Pull Request Overview

The PR replaces the deprecated Travis CI configuration with a modern GitHub Actions workflow, expands testing across multiple Java versions, and adds unit-test result publishing.

• Removed .travis.yml as it is no longer used.
• Updated .github/workflows/build.yml to run on pushes and PRs to main/master, bumped Action versions, and added a Java matrix including JDK 8, 11, 17, and 21.
• Added a step to publish JUnit test results after the Maven build.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
.travis.yml	Deleted unused Travis CI config
.github/workflows/build.yml	Migrated CI to GitHub Actions, added Java version matrix, and test-report publishing

Comments suppressed due to low confidence (3)

.github/workflows/build.yml:34

• Expand the test report glob to include integration test outputs (e.g., target/failsafe-reports/*.xml) to ensure complete coverage in the published results.

files: target/surefire-reports/*.xml

.github/workflows/build.yml:8

• [nitpick] If your repository has standardized on 'main' as the default branch, consider removing 'master' to simplify workflow triggers and avoid unused pipeline runs.

branches: [ main, master ]

.github/workflows/build.yml:15

• [nitpick] Consider adding 'fail-fast: false' under the strategy to ensure all JDK matrix jobs run even if one fails, providing a full view of compatibility issues.

strategy: