Quieten ssl tests (#952)

* Add skip when required TLS version unsupported

Allow tests to skip, rather than fail from SSL errors with unsupported
TLS version, e.g. if Openssl is configured with MinProtocol higher than
the version being tested.

* Regenerate test certificate and key

Regenerate these with more secure settings for the sake of future
proofing, regenerate the key using RSA 4096 and sign the certificate
with SHA512.

This fixes test failures in tests/test_ssl.py when the user's OpenSSL
security level is set to a value greater than 1 and resolves issue #948

* Suppress SSL warnings in no verify tests

tests/test_ssl.py

@@ -1,6 +1,8 @@
 import pytest
 import pytest_httpbin.certs
 import requests.exceptions
+import ssl
+import urllib3
 
 from httpie.ssl import AVAILABLE_SSL_VERSION_ARG_MAPPING, DEFAULT_SSL_CIPHERS
 from httpie.status import ExitStatus
@@ -46,6 +48,12 @@ def test_ssl_version(httpbin_secure, ssl_version):
         if ssl_version == 'ssl3':
             # pytest-httpbin doesn't support ssl3
             pass
+        elif e.__context__ is not None:  # Check if root cause was an unsupported TLS version
+            root = e.__context__
+            while root.__context__ is not None:
+                root = root.__context__
+            if isinstance(root, ssl.SSLError) and root.reason == "TLSV1_ALERT_PROTOCOL_VERSION":
+                pytest.skip("Unsupported TLS version: {}".format(ssl_version))
         else:
             raise
 
@@ -84,11 +92,14 @@ class TestClientCert:
 class TestServerCert:
 
     def test_verify_no_OK(self, httpbin_secure):
+        # Avoid warnings when explicitly testing insecure requests
+        urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
         r = http(httpbin_secure.url + '/get', '--verify=no')
         assert HTTP_OK in r
 
     @pytest.mark.parametrize('verify_value', ['false', 'fALse'])
     def test_verify_false_OK(self, httpbin_secure, verify_value):
+        urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
         r = http(httpbin_secure.url + '/get', '--verify', verify_value)
         assert HTTP_OK in r