Add a release note

Author: abonie

docs/release-notes/.FSharp.Compiler.Service/9.0.100.md

@@ -13,6 +13,7 @@
 * Fixed checking failure when `global` namespace is involved with enabled GraphBasedChecking ([PR #17553](https://github.com/dotnet/fsharp/pull/17553))
 * Add missing byte chars notations, enforce limits in decimal notation in byte char & string (Issues [#15867](https://github.com/dotnet/fsharp/issues/15867), [#15868](https://github.com/dotnet/fsharp/issues/15868), [#15869](https://github.com/dotnet/fsharp/issues/15869), [PR #15898](https://github.com/dotnet/fsharp/pull/15898))
 * Parentheses analysis: keep extra parentheses around unit & tuples in method definitions. ([PR #17618](https://github.com/dotnet/fsharp/pull/17618))
+* Fix IsUnionCaseTester throwing for non-methods/properties [#17301](https://github.com/dotnet/fsharp/pull/17634)
 
 ### Added