[KYUUBI apache#6071] Add .java-version into git ignore

# 🔍 Description
## Issue References 🔗

This pull request fixes apache#6071

## Describe Your Solution 🔧

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

## Types of changes 🔖

- [ ] Bugfix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to change)

## Test Plan 🧪

#### Behavior Without This Pull Request ⚰️

#### Behavior With This Pull Request 🎉

#### Related Unit Tests

---

# Checklist 📝

- [ ] This patch was not authored or co-authored using [Generative Tooling](https://www.apache.org/legal/generative-tooling.html)

**Be nice. Be informative.**

Closes apache#6072 from yanghua/kyuubi-6071.

Closes apache#6071

cae4a47 [yanghua] [KYUUBI apache#6071] Add .java-version into git ignore

Authored-by: yanghua <[email protected]>
Signed-off-by: Cheng Pan <[email protected]>

.gitignore

@@ -75,6 +75,7 @@ embedded_zookeeper/
 conf/log4j2.xml
 conf/kyuubi-defaults.conf
 conf/kyuubi-env.sh
+.java-version
 
 # For Antlr
 kyuubi-server/gen