Bump lmfit dependency to >=1.3.4,<2

Updated the lmfit package version requirement in pyproject.toml from >=1.2.2 to >=1.3.4 to ensure compatibility with newer features or bug fixes.

Author: JR-1991

pyproject.toml

@@ -23,7 +23,7 @@ dependencies = [
   "numpyro>=0.19.0,<0.20.0",
   "arviz>=0.22.0,<0.30.0",
   "corner>=2.2.2,<3",
-  "lmfit>=1.2.2,<2",
+  "lmfit>=1.3.4,<2",
   "jinja2>=3.1.2,<4",
   "ipywidgets>=8.1.1,<9",
   "optax>=0.2.5,<0.3",