👷 ci: run the test matrix against Python 3.15 (#4001)

Author: gaborbernat

.github/workflows/check.yaml

@@ -22,6 +22,7 @@ jobs:
       fail-fast: false
       matrix:
         py:
+          - "3.15"
           - "3.14"
           - "3.13"
           - "3.12"

.github/workflows/weekly.yaml

@@ -0,0 +1 @@
+Test against Python 3.15 (beta) in CI and declare its classifier - by :user:`gaborbernat`.

docs/changelog/4001.misc.rst

@@ -41,6 +41,7 @@ classifiers = [
   "Programming Language :: Python :: 3.12",
   "Programming Language :: Python :: 3.13",
   "Programming Language :: Python :: 3.14",
+  "Programming Language :: Python :: 3.15",
   "Topic :: Software Development :: Libraries",
   "Topic :: Software Development :: Testing",
   "Topic :: Utilities",
@@ -216,7 +217,7 @@ write-changes = true
 count = true
 
 [tool.pyproject-fmt]
-max_supported_python = "3.14"
+max_supported_python = "3.15"
 
 [tool.ty]
 src.exclude = []