Update jupyter-book requirement from ==0.15.* to ==1.0.*

Updates the requirements on [jupyter-book](https://github.com/executablebooks/jupyter-book) to permit the latest version.
- [Release notes](https://github.com/executablebooks/jupyter-book/releases)
- [Changelog](https://github.com/executablebooks/jupyter-book/blob/master/CHANGELOG.md)
- [Commits](jupyter-book/jupyter-book@v0.15.0...v1.0.0)

---
updated-dependencies:
- dependency-name: jupyter-book
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements-docs.txt

@@ -1,3 +1,3 @@
 # For documentation
 ghp-import==2.1.*
-jupyter-book==0.15.*
+jupyter-book==1.0.*