Added a PR template and an "in progress" changelog

.github/pull_request_template.md

@@ -0,0 +1,22 @@
+This Pull request fixes #xx, fixes #yy, fixes #zz
+
+ - [ ] I completed the issue numbers (#xx) in the sentence above. The word "fixes" should remain in front of each issue
+ - [ ] My PR is tagged as draft when I'm still working on it, and I remove the draft flag when it is ready for review.
+- [ ] I added one or several `changelog.md` entries in the appropriate "in progress" section (not the last release one)
+
+### b - My PR adds some features:
+
+*(Delete this section if not relevant)*
+
+ - [ ] Each issue is well-described, well-labeled and explains/agrees on the expected solution (high-level).
+ - [ ] I added documentation gallery examples showing the new features
+ - [ ] I created tests for each new feature. In particular I have for each feature:
+   - [ ] nominal tests (several simple ones or a parametrized one, or both)
+   - [ ] edge tests (valid but very particular cases, for example empty data, daylight savings change day, sparse matrix, etc.)
+   - [ ] error tests (in which case use `with pytest.raises(MyErrorType, match="...")`)
+
+### b - My PR fixes some issues:
+
+*(Delete this section if not relevant)*
+
+ - [ ] Each issue is well-described, well-labeled, and contains reproducible code examples.

docs/changelog.md

@@ -1,5 +1,9 @@
 # Changelog
 
+### 0.7.9 - (In Progress)
+
+ - TBD
+
 ### 0.7.8 - Bugfixes
 
  - Fixed `Plugin 'gallery' option 'binder': Sub-option 'org': Required configuration not provided.`. Fixes [#62](https://github.com/smarie/mkdocs-gallery/issues/62)