[Chore] Add pull request template for plugin (#61)

.github/PULL_REQUEST_TEMPLATE

+<!-- Uncomment the following checklist WHEN AND ONLY WHEN you're adding a new plugin -->
+<!--
+- [ ] Add a test case for the new plugin
+- [ ] Add a component id in [the main repo](https://github.com/apache/skywalking/blob/master/oap-server/server-bootstrap/src/main/resources/component-libraries.yml#L415)
+- [ ] Add a logo in [the UI repo](https://github.com/apache/skywalking-rocketbot-ui/tree/master/src/views/components/topology/assets)
+- [ ] Add the library/module that this plugin instruments into the `setup.py` (`extras_require/test`), such as `pymysql`, `flask`, `django`, etc.
+- [ ] Rebuild the `requirements.txt` by running `tools/env/build_requirements_(linux|windows).sh`
+-->

setup.py

@@ -52,6 +52,7 @@ setup(
             "kafka-python",
             "tornado",
             "pika",
+            "pymongo",
         ],
     },
     classifiers=[