Add Github issue template.

Author: elprans

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,21 @@
+<!--
+Thanks for wanting to report an issue you've found in asyncpg. Please fill in
+the template below.
+
+It will be much easier for us to fix the issue if a test case that reproduces
+the problem is provided, with clear instructions on how to run it.
+
+Thank you!
+-->
+
+* **asyncpg version**:
+* **PostgreSQL version**:
+* **Python version**:
+* **Platform**:
+* **Do you use pgbouncer?**:
+* **Do you use the wheel package or built locally
+ (if locally, which version of Cython was used)?**:
+* **Can you the issue be reproduced when running under
+ [uvloop](https://github.com/magicstack/uvloop)?**:
+
+<!-- Enter your issue details below this comment. -->