Bump version to v3.1.5.

Author: nyibbang

pyproject.toml

@@ -7,7 +7,7 @@ build-backend = "scikit_build_core.build"
 [project]
 name = "qi"
 description = "LibQi Python bindings"
-version = "3.1.5.dev0"
+version = "3.1.5"
 readme = "README.rst"
 requires-python = ">=3.7"
 license = { "file" = "COPYING" }