Python: Add test of public_key method with cryptodome

Added in 3.10 release https://github.com/Legrandin/pycryptodome/blob/master/Changelog.rst#3100-6-february-2021

Author: RasmusWL

python/ql/test/experimental/library-tests/frameworks/crypto/test_rsa.py

@@ -6,7 +6,10 @@
 from Crypto.Hash import SHA256
 
 private_key = RSA.generate(2048) # $ PublicKeyGeneration keySize=2048
+
+# These 2 methods do the same
 public_key = private_key.publickey()
+public_key = private_key.public_key()
 
 # ------------------------------------------------------------------------------
 # encrypt/decrypt

python/ql/test/experimental/library-tests/frameworks/cryptodome/test_rsa.py

@@ -6,7 +6,10 @@
 from Cryptodome.Hash import SHA256
 
 private_key = RSA.generate(2048) # $ PublicKeyGeneration keySize=2048
+
+# These 2 methods do the same
 public_key = private_key.publickey()
+public_key = private_key.public_key()
 
 # ------------------------------------------------------------------------------
 # encrypt/decrypt