Force plugin to use TLS v1.2 instead of v1.3.

This is needed due to a change on Adobe's end, breaking
Python > 3.7.16.

Fixes #105.

calibre-plugin/libadobe.py

@@ -294,7 +294,13 @@ def sendHTTPRequest_getSimple(URL):
  # It appears as if lots of book distributors have either invalid or expired certs ...
  # No idea how Adobe handles that (pinning?), but we can just ignore SSL errors and continue anyways.
  # Not the best solution, but it works.
- ctx = ssl.create_default_context()
+ try: 
+ ctx = ssl.SSLContext(ssl.PROTOCOL_TLSv1_2)
+ # This is needed due to an Adobe change. 
+ # Without this, only Python <= 3.7.16 can connect, 3.7.17 and above fail.
+ except:
+ ctx = ssl.create_default_context()
+
  ctx.check_hostname = False
  ctx.verify_mode = ssl.CERT_NONE
 
@@ -328,7 +334,13 @@ def sendPOSTHTTPRequest(URL, document, type, returnRC = False):
  # It appears as if lots of book distributors have either invalid or expired certs ...
  # No idea how Adobe handles that (pinning?), but we can just ignore SSL errors and continue anyways.
  # Not the best solution, but it works.
- ctx = ssl.create_default_context()
+ try: 
+ ctx = ssl.SSLContext(ssl.PROTOCOL_TLSv1_2)
+ # This is needed due to an Adobe change. 
+ # Without this, only Python <= 3.7.16 can connect, 3.7.17 and above fail.
+ except:
+ ctx = ssl.create_default_context()
+
  ctx.check_hostname = False
  ctx.verify_mode = ssl.CERT_NONE