Update scipy requirement from <1.15 to <1.16

Updates the requirements on [scipy](https://github.com/scipy/scipy) to permit the latest version.
- [Release notes](https://github.com/scipy/scipy/releases)
- [Commits](scipy/scipy@v0.1.0...v1.15.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

pyproject.toml

@@ -27,7 +27,7 @@ tinygp = "^0.3.0"
 seaborn = "^0.13.1"
 sparse = "^0.15.4"
 optimistix = ">=0.0.7,<0.0.10"
-scipy = "<1.15"
+scipy = "<1.16"
 mendeleev = ">=0.15,<0.20"
 jaxns = "<2.6"
 pooch = "^1.8.2"