fix: Get rsa.decrypt working

[cpswan]

rsa.decrypt was always failing as this test always returned true:

if cleartext[0:2] != b'\x00\x02':

It seems that the leading characters for the cleartext we're getting are b' \x02' - a space instead of a null

This isn't happening at the padding stage before encryption, which is correct. But I've not been able to track down where that b'\x20' is creeping in.

- What I did

Allow the test to pass when it finds b' \x02' (as well as b'\x00\x02')

Also added pycache to .gitignore

- How I did it

Looked at raw cleartext to see why the test was failing and observed a leading space rather than the null that should be there.

- How to verify it

import sys
import ubinascii
sys.path.append('./lib')
from pem_service import get_pem_parameters, get_pub_parameters, get_pem_key
from third_party import rsa
encryptpub='A_PEM_encoded_RSA_public_key'
encryptpriv='A_PEM_encoded_RSA_private_key'
pubKey = get_pub_parameters(encryptpub)
print(pubKey)
rsapub = rsa.PublicKey(pubKey[0], pubKey[1])
privKey = get_pem_parameters(get_pem_key(encryptpriv))
print(privKey)
rsapriv = rsa.PrivateKey(privKey[0], privKey[1], privKey[2], privKey[3], privKey[4])
enchello = rsa.encrypt(b'hello world', rsapub)
print(rsa.decrypt(enchello, rsapriv))

- Description for the changelog

fix: Get rsa.decrypt working