In bug template, ask for Python version in addition to Cython version

.github/ISSUE_TEMPLATE/bug_report.md

@@ -27,7 +27,8 @@ A clear and concise description of what you expected to happen.
 
 **Environment (please complete the following information):**
  - OS: [e.g. Linux, Windows, macOS]
- - Version [e.g. 0.29.18]
+ - Python version [e.g. 3.8.4]
+ - Cython version [e.g. 0.29.18]
 
 **Additional context**
 Add any other context about the problem here.