test: mark test-crypto-keygen slow on windows

Refs: #41206

This test seems to be failing regularly on
windows with a timeout. Mark it slow to reduce
CI noise until it gets investigated.

Signed-off-by: Michael Dawson <mdawson@devrus.com>

PR-URL: #41207
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/parallel.status

@@ -11,6 +11,8 @@ prefix parallel
 test-timers-immediate-queue: PASS,FLAKY
 # https://github.com/nodejs/node/issues/23277
 test-worker-memory: PASS,FLAKY
+# https://github.com/nodejs/node/issues/41206
+test-crypto-keygen: PASS,FLAKY
 
 [$system==linux]
 # https://github.com/nodejs/node/issues/39368