Update agate requirement from ~=1.7.0 to ~=1.9.1

Updates the requirements on [agate](https://github.com/wireservice/agate) to permit the latest version.
- [Changelog](https://github.com/wireservice/agate/blob/master/CHANGELOG.rst)
- [Commits](wireservice/agate@1.7.0...1.9.1)

---
updated-dependencies:
- dependency-name: agate
  dependency-type: direct:production
...

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

pyproject.toml

@@ -20,7 +20,7 @@ classifiers = [
   "Programming Language :: Python :: Implementation :: PyPy",
 ]
 dependencies = [
-  "agate~=1.7.0",
+  "agate~=1.9.1",
   "colorama>=0.3.9,<0.5",
   "isodate>=0.6,<0.7",
   "jsonschema~=4.0",