Loosen pydantic-settings pin from ==2.0.* to >=2.0,<3 (#125)

The current pin to pydantic-settings==2.0.* conflicts with other packages
that require pydantic-settings>=2.8.1 (e.g. davies-cli), making it
impossible for dependency resolvers to find a compatible set of packages
when centml is installed alongside them.

Widening to >=2.0,<3 follows semver and allows co-installation with
packages that depend on newer pydantic-settings releases.

Author: astaff

requirements.txt

@@ -1,7 +1,7 @@
 fastapi>=0.103.0
 uvicorn>=0.23.0
 python-multipart>=0.0.6
-pydantic-settings==2.0.*
+pydantic-settings>=2.0,<3
 Requests==2.32.4
 tabulate>=0.9.0
 pyjwt>=2.8.0