use tbump to bump versions

ensures baseVersion is always in sync with tag

Author: minrk

RELEASE.md

@@ -65,8 +65,7 @@ Also the images we build are based on some image specified in the `FROM` stateme
     ```bash
     git checkout main
     git reset --hard <upstream>/main
-    git tag -a x.y.z-beta.1 -m x.y.z-beta.1 <commit on main>
-    git push --follow-tags <upstream> main
+    tbump x.y.z-beta.1
     ```
 
 - Announce the x.y.z-beta.1 release
@@ -89,11 +88,14 @@ Also the images we build are based on some image specified in the `FROM` stateme
     ```bash
     git checkout main
     git reset --hard <upstream>/main
-    git tag -a x.y.z -m x.y.z HEAD
-    git push --follow-tags <upstream> main
+    tbump x.y.z
     ```
 
-  - [ ] Update baseVersion in chartpress to the next release (e.g. `2.1.0-0.dev` after 2.0.0)
+  - [ ] Set the next prerelease version (don't create a tag).
+
+    ```bash
+    tbump --no-tag x.y+1.z-0.dev
+    ```
 
   - [ ] Create a GitHub release.
         Visit the [release page](https://github.com/jupyterhub/zero-to-jupyterhub-k8s/releases) and create a new release referencing the recent tag. Add a brief text like the one below.

dev-requirements.txt

@@ -17,3 +17,6 @@ click
 
 # used to formatting and linting
 pre-commit>=2.0.0
+
+# used for tagging releases
+tbump

tbump.toml

@@ -0,0 +1,35 @@
+# tbump config sets baseVersion in chartpress.yaml
+[version]
+current = "2.0.0-0.dev"
+
+# match our prerelease prefixes
+# -alpha.1
+# -beta.2
+# -0.dev
+
+regex = '''
+  (?P<major>\d+)
+  \.
+  (?P<minor>\d+)
+  \.
+  (?P<patch>\d+)
+  (\-
+    (?P<prelease>
+      (
+       (alpha|beta|rc)\.\d+|
+       0\.dev
+      )
+    )
+  )?
+  '''
+
+[git]
+message_template = "Bump to {new_version}"
+tag_template = "{new_version}"
+
+# For each file to patch, add a [[file]] config
+# section containing the path of the file, relative to the
+# tbump.toml location.
+[[file]]
+src = "chartpress.yaml"
+search = 'baseVersion: "{current_version}"'