bpo-31518: Change TLS protocol for Debian (#3661)

Debian Unstable has disabled TLS 1.0 and 1.1 for SSLv23_METHOD(). Change
TLS/SSL protocol of some tests to PROTOCOL_TLS or PROTOCOL_TLSv1_2 to
make them pass on Debian.

Signed-off-by: Christian Heimes <christian@python.org>
diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
index 7e8b058..44ffac7 100644
--- a/Lib/test/test_httplib.py
+++ b/Lib/test/test_httplib.py
@@ -860,7 +860,7 @@
         import ssl
         test_support.requires('network')
         with test_support.transient_internet('self-signed.pythontest.net'):
-            context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
+            context = ssl.SSLContext(ssl.PROTOCOL_TLS)
             context.verify_mode = ssl.CERT_REQUIRED
             context.load_verify_locations(CERT_selfsigned_pythontestdotnet)
             h = httplib.HTTPSConnection('self-signed.pythontest.net', 443, context=context)
@@ -874,7 +874,7 @@
         import ssl
         test_support.requires('network')
         with test_support.transient_internet('self-signed.pythontest.net'):
-            context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
+            context = ssl.SSLContext(ssl.PROTOCOL_TLS)
             context.verify_mode = ssl.CERT_REQUIRED
             context.load_verify_locations(CERT_localhost)
             h = httplib.HTTPSConnection('self-signed.pythontest.net', 443, context=context)
@@ -895,7 +895,7 @@
         # The (valid) cert validates the HTTP hostname
         import ssl
         server = self.make_server(CERT_localhost)
-        context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
+        context = ssl.SSLContext(ssl.PROTOCOL_TLS)
         context.verify_mode = ssl.CERT_REQUIRED
         context.load_verify_locations(CERT_localhost)
         h = httplib.HTTPSConnection('localhost', server.port, context=context)
@@ -907,7 +907,7 @@
         # The (valid) cert doesn't validate the HTTP hostname
         import ssl
         server = self.make_server(CERT_fakehostname)
-        context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
+        context = ssl.SSLContext(ssl.PROTOCOL_TLS)
         context.verify_mode = ssl.CERT_REQUIRED
         context.check_hostname = True
         context.load_verify_locations(CERT_fakehostname)