ci: test the dependency floors on Python 3.15

.github/workflows/_checks.yml

@@ -84,6 +84,8 @@ jobs:
           - "3.13"
           - "3.14"
           - "3.14t"
+          - "3.15"
+          - "3.15t"
     services:
       redis:
         image: redis:8

pyproject.toml

@@ -26,14 +26,16 @@ dependencies = [
     # 5.0.1 is the first release with Redis.aclose, which the broker calls on teardown.
     "redis>=5.0.1",
     # Not imported here: faststream pulls pydantic through fast-depends[pydantic], and pydantic-core
-    # ships no cp314 wheel before pydantic 2.12, so the lowest declared combination has no
-    # installable pydantic on 3.14.
-    "pydantic>=2.12; python_version >= '3.14'",
+    # ships no cp314 wheel before pydantic 2.12 and no cp315 wheel before 2.14, so the lowest
+    # declared combination has no installable pydantic on 3.14 or 3.15.
+    "pydantic>=2.12; python_version == '3.14'",
+    "pydantic>=2.14; python_version >= '3.15'",
     # 4.12.2, not 4.12.0: pydantic requires >=4.12.2 on 3.13+, and pinning 4.12.0 drags pydantic
     # back to a build whose pydantic-core has no cp313 wheel either.
     "typing-extensions>=4.12.2",
-    # pydantic 2.12, the 3.14 floor above, requires >=4.14.1.
-    "typing-extensions>=4.14.1; python_version >= '3.14'",
+    # pydantic 2.12 and 2.14, the 3.14 and 3.15 floors above, require >=4.14.1 and >=4.16.0.
+    "typing-extensions>=4.14.1; python_version == '3.14'",
+    "typing-extensions>=4.16.0; python_version >= '3.15'",
 ]
 
 [dependency-groups]