Change development status to stable

With the switch to version 1.0.0 and the very low frequency of updates,
this library can be considered stable. Should I eventually decide to
finally do some deprecations and/or remove functionality, it will be
done in version 2 major.

Author: FichteFoll

pyproject.toml

@@ -15,7 +15,7 @@ requires-python = ">=3.8"
 license = "MIT"
 license-files = ["LICENSE"]
 classifiers = [
-    "Development Status :: 4 - Beta",
+    "Development Status :: 5 - Production/Stable",
     "Intended Audience :: Developers",
     "Operating System :: OS Independent",
     "Programming Language :: Python :: 3",