Update Manual Release Instructions (jupyter#6152)

* Update RELEASE.md

Use `jupyter_releaser` for its build dependencies (`build`, `twine`, `tbump`)

* Update RELEASE.md

Author: Steven Silvester

RELEASE.md

@@ -38,15 +38,15 @@ pip install -ve .
 ### Install release dependencies
 
 ```bash
-conda install -c conda-forge nodejs babel twine build
+conda install -c conda-forge nodejs babel
 npm install -g po2json
+pip install jupyter_releaser  # used for build dependencies (build, twine, tbump)
 ```
 
 ### Update the version
 
 ```bash
-vim notebook/_version.py  # update version
-vim pyproject.toml  # update version to match
+tbump --only-patch <new_version> # set the new version
 python setup.py jsversion
 git commit -am "Release $(python setup.py --version)"
 git tag $(python setup.py --version)
@@ -68,7 +68,7 @@ twine check dist/* && twine upload dist/*
 ### Change back to dev version
 
 ```bash
-vim notebook/_version.py   # Add the .dev suffix
+tbump --only-patch <dev_version>  # Add the .dev suffix
 python setup.py jsversion
 git commit -am "Back to dev version"
 ```