Fix a Windows build error in the test suite

The definition of `withApp` was mistakenly guarded behind CPP that is not
reachable on Windows, but `withApp` is also needed outside of the CPP.

test/Web/ScottySpec.hs

@@ -36,6 +36,7 @@ availableMethods = [GET, POST, HEAD, PUT, PATCH, DELETE, OPTIONS]
 
 spec :: Spec
 spec = do
+  let withApp = with . scottyApp
   describe "ScottyM" $ do
     forM_ [
         ("GET", Scotty.get, get)
@@ -186,8 +187,6 @@ spec = do
         ok = "HTTP/1.1 200 OK"
         no = "HTTP/1.1 404 Not Found"
 
-        withApp = with . scottyApp
-
 socketPath :: FilePath
 socketPath = "/tmp/scotty-test.socket"