chore: Track flagsmith-dotnet-sdk 9.0.0 (#6379)

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

Author: 3 people

api/app_analytics/constants.py

@@ -19,7 +19,10 @@
 # because, when we prepare the data for Influx, we need to map to numeric IDs.
 # This allows us to efficiently store usage and evaluation data.
 SDK_USER_AGENT_KNOWN_VERSIONS: dict[KnownSDK, list[str]] = {
-    "flagsmith-dotnet-sdk": ["unknown"],
+    "flagsmith-dotnet-sdk": [
+        "unknown",
+        "9.0.0",
+    ],
     "flagsmith-elixir-sdk": [
         "unknown",
         "2.3.0",