Update validate-pyproject requirement from <0.15 to <0.16

Updates the requirements on [validate-pyproject](https://github.com/abravalheri/validate-pyproject) to permit the latest version.
- [Release notes](https://github.com/abravalheri/validate-pyproject/releases)
- [Changelog](https://github.com/abravalheri/validate-pyproject/blob/main/CHANGELOG.rst)
- [Commits](abravalheri/validate-pyproject@v0.0.1...v0.15)

---
updated-dependencies:
- dependency-name: validate-pyproject
  dependency-type: direct:production
...

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

pyproject.toml

@@ -74,7 +74,7 @@ develop = [
   "poethepoet<1",
   "pyproject-fmt<1.3",
   "ruff==0.0.292",
-  "validate-pyproject<0.15",
+  "validate-pyproject<0.16",
 ]
 release = [
   "build<2",