docs: ask for the Java version in the bug report template

The Environment Details section of the bug report template asks for
"TS Version (tsc --version)", which does not apply to a Java project.
The template asked for the Java version until 3e74c9a refined it.
Reporters now answer the line with N/A, and some write their JDK
version next to it. adk-python asks for the Python version
(python -V) and adk-go for the Go version in the same place.

Ask for the Java version (java -version) again.

Author: innoprej

.github/ISSUE_TEMPLATE/bug_report.md

@@ -35,7 +35,7 @@ What actually happened? Include error messages or crash stack traces here.
 
  - ADK Library Version (see maven dependency):
  - OS: [e.g., macOS, Linux, Windows]
- - TS Version (tsc --version):
+ - Java Version (java -version):
 
 **Model Information:**