Remove unreachable null check from toQueryParams fallthrough case (#306)

* Initial plan

* Fix toQueryParams: remove unreachable null check from _ case

Co-authored-by: sergey-tihon <1197905+sergey-tihon@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: sergey-tihon <1197905+sergey-tihon@users.noreply.github.com>

Author: Copilot

src/SwaggerProvider.Runtime/RuntimeHelpers.fs

@@ -116,7 +116,7 @@ module RuntimeHelpers =
         | :? DateTime as x -> [ name, x.ToString("O") ]
         | :? DateTimeOffset as x -> [ name, x.ToString("O") ]
         | :? Option<Guid> as x -> x |> toStrOpt name
-        | _ -> [ name, (if isNull obj then null else obj.ToString()) ]
+        | _ -> [ name, obj.ToString() ]
 
     let getPropertyNameAttribute name =
         { new Reflection.CustomAttributeData() with