chore: Drop Python 3.9 support from ci (#2161)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: bhimrazy

.github/workflows/cpu-tests.yml

@@ -80,10 +80,10 @@ jobs:
       fail-fast: false
       matrix:
         os: ["ubuntu-22.04"]
-        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.10", "3.11", "3.12", "3.13"]
         requires: ["latest"]
         include:
-          - { os: "ubuntu-22.04", python-version: "3.9", requires: "oldest" }
+          - { os: "ubuntu-22.04", python-version: "3.10", requires: "oldest" }
           - { os: "windows-2022", python-version: "3.10", requires: "latest" }
           - { os: "macOS-14", python-version: "3.10", requires: "latest" }
     timeout-minutes: 35

pyproject.toml

@@ -16,9 +16,9 @@ license = { file = "LICENSE" }
 authors = [
   { name = "Lightning AI", email = "[email protected]" },
 ]
+requires-python = ">=3.10"
 classifiers = [
   "Programming Language :: Python :: 3 :: Only",
-  "Programming Language :: Python :: 3.9",
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",
@@ -27,8 +27,7 @@ classifiers = [
 dependencies = [
   # download models:
   "huggingface-hub>=0.30,<0.35",
-  "jsonargparse[signatures]>=4.31,<=4.32.1; python_version<'3.10'", # 4.33 does not seem to be compatible with Python 3.9
-  "jsonargparse[signatures]>=4.37,<=4.41; python_version>'3.9'",    # required to work with python3.12+
+  "jsonargparse[signatures]>=4.37,<=4.41; python_version>='3.10'", # required to work with Python >=3.10
   "lightning>=2.5",
   "psutil==7",
   "safetensors>=0.4.3",