tests: patch localtime in the "cert remainingdays" test

to make sure the code where the invalid timezone is passed to exercise
the localtime code path doesn't fail as time goes by.

The other test was added to exercise the code path where the second
format is passed.

Author: evverx

test/scapy/layers/tls/cert.uts

@@ -329,7 +329,13 @@ x.notAfter == (2026, 3, 30, 7, 38, 59, 0, 89, -1)
 
 = Cert class : test remainingDays
 assert abs(x.remainingDays("02/12/11")) > 5000
-assert abs(x.remainingDays("Feb 12 10:00:00 2011 Paris, Madrid")) > 1
+assert abs(x.remainingDays("Feb 12 10:00:00 2011 UTC")) > 5000
+
+from unittest.mock import patch
+import time
+
+with patch('time.localtime', return_value=time.struct_time((2026, 3, 29, 7, 38, 58, 6, 88, 0))):
+    assert abs(x.remainingDays("Feb 12 10:00:00 2011 Paris, Madrid")) > 1
 
 = Cert class : Checking RSA public key
 assert type(x.pubkey) is PubKeyRSA
@@ -1104,4 +1110,4 @@ assert [x.buffer for x in aikOpaque.policyDigestList.digests] == [
     b'\xc4\x13\xa8G\xb1\x11\x12\xb1\xcb\xdd\xd4\xec\xa4\xda\xaa\x15\xa1\x85,\x1c;\xbaWF\x1d%v\x05\xf3\xd5\xafS',
     b'',
     b'\x04\x8e\x9a:\xce\x08X?y\xf3D\xffx[\xbe\xa9\xf0z\xc7\xfa3%\xb3\xd4\x9a!\xddQ\x94\xc6XP',
-]
+]