CI: Add Python 3.14 unit tests (#10511)

* Add Python 3.14 unit tests.

* Skip test if github cannot be imported.

It currently cannot be imported because nacl isn't compatible with Python 3.14 yet,
and importing github indirectly tries to import nacl, which fails as it uses a
type from typing that got removed in 3.14.

* Skip test if paramiko cannot be imported.

.azure-pipelines/azure-pipelines.yml

@@ -124,7 +124,7 @@ stages:
             - test: '3.11'
             - test: '3.12'
             - test: '3.13'
-            # - test: '3.14'
+            - test: '3.14'
   - stage: Units_2_19
     displayName: Units 2.19
     dependsOn: []