Update minimum typing-extensions pin on python3.14 (#43425)

* override typing-extensions dep on py3.14. it's breaking pydactic-core
* fix typing-extensions specifier from >- to >=

Author: scbedd

eng/tox/install_depend_packages.py

@@ -70,6 +70,9 @@
 # PLATFORM SPECIFIC OVERRIDES provide additional generic (EG not tied to the package whos dependencies are being processed)
 # filtering on a _per platform_ basis. Primarily used to limit certain packages due to platform compat
 PLATFORM_SPECIFIC_MINIMUM_OVERRIDES = {
+    ">=3.14.0": {
+        "typing-extensions": "4.15.0",
+    },
     ">=3.12.0": {
         "azure-core": "1.23.1",
         "aiohttp": "3.9.0",