[ruby/openssl] ns_spki: update keys used in tests

Use generic keys whenever possible.

ruby/openssl@ef4fa5e9b4

Author: rhenium

test/openssl/test_ns_spki.rb

@@ -17,8 +17,8 @@ def setup
   end
 
   def test_build_data
-    key1 = Fixtures.pkey("rsa1024")
-    key2 = Fixtures.pkey("rsa2048")
+    key1 = Fixtures.pkey("rsa-1")
+    key2 = Fixtures.pkey("rsa-2")
     spki = OpenSSL::Netscape::SPKI.new
     spki.challenge = "RandomString"
     spki.public_key = key1.public_key