PCSCCardConnection.__del__: ignore SCARD_E_INVALID_VALUE error

In some cases the value self.hcontext becomes invalid before
SCardReleaseContext() is called. This happens if the reader is removed
for example.

The problem was visible when using a smartcard.Session() and we
disconnect the reader before the end of the session. When the program
exists we had something like:

Exception ignored in: <function PCSCCardConnection.__del__ at 0x7f8fb65957e0>
Traceback (most recent call last):
  File "/usr/local/lib/python3.10/dist-packages/pyscard-2.0.3-py3.10-linux-x86_64.egg/smartcard/pcsc/PCSCCardConnection.py", line 90, in __del__
smartcard.Exceptions.CardConnectionException: Failed to release context: Invalid value given.

Thanks to Frank Morgner for the bug report
" Quitting Session causes "Exception ignored in" LudovicRousseau#131 "
LudovicRousseau#131

smartcard/pcsc/PCSCCardConnection.py

@@ -86,7 +86,7 @@ def __del__(self):
         # can disappear before __del__ is called
         self.disconnect()
         hresult = SCardReleaseContext(self.hcontext)
-        if hresult != 0:
+        if hresult != 0 and hresult != SCARD_E_INVALID_VALUE:
             raise CardConnectionException(
                 'Failed to release context: ' + \
                 SCardGetErrorMessage(hresult))