Set up issue templates

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,31 @@
+---
+name: Bug report
+about: Report a problem or unexpected error
+title: ''
+labels: bug
+assignees: ''
+
+---
+
+**Description**
+A clear and concise description of the problem.
+
+**Reproducible example**
+Include a short code snippet to reproduce the problem.
+
+```python
+import snail
+input = {"example": "data"}
+output = snail.do_something(input)
+```
+
+<details><summary>Error message</summary>
+
+```
+Copy-paste a stack trace
+```
+
+</details>
+
+**Expected behavior**
+What did you expect to happen instead?

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,14 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: feature
+assignees: ''
+
+---
+
+**Problem statement**
+A short description of the problem or need - what would this feature solve?
+
+**Suggested approach**
+Initial ideas for how to solve it - what should we do?

.github/ISSUE_TEMPLATE/release-snail.md

@@ -0,0 +1,19 @@
+---
+name: Release snail
+about: Checklist to follow for release
+title: "(release) v0."
+labels: ''
+assignees: ''
+
+---
+
+Follow these steps:
+- [ ] Merge all desired PRs to `main`, let CI tests pass
+- [ ] Update version number in `pyproject.toml`
+- [ ] Push to `main`
+- [ ] Start drafting a new release at [https://github.com/nismod/snail/releases/new](https://github.com/nismod/snail/releases/new)
+  - [ ] Create a new tag: click "Choose a tag", enter new version number (e.g. `v0.5.2`), click "Create new tag on publish"
+  - [ ] Click "Generate release notes" (this should give the release the same title as the tag (e.g. "v0.5.2")
+  - [ ] Edit the "What's New" section into "Features" and "Fixes", simplify and combine PR bullet points
+  - [ ] Publish release
+- [ ] Wait for CI to run - this should trigger the "package" workflow in GitHub Actions and push to [PyPI](https://pypi.org/project/nismod-snail/#history)