Log Message:
py-urllib3: updated to 1.24

1.24:
Allow key_server_hostname to be specified when initializing a PoolManager to \ 
allow custom SNI to be overridden.
Test against Python 3.7 on AppVeyor.
Early-out ipv6 checks when running on App Engine.
Change ambiguous description of backoff_factor
Add ability to handle multiple Content-Encodings
Skip DNS names that can't be idna-decoded when using pyOpenSSL
Add a server_hostname parameter to HTTPSConnection which allows for overriding \ 
the SNI hostname sent in the handshake.
Drop support for EOL Python 2.6
Fixed bug where responses with header Content-Type: message/* erroneously raised \ 
HeaderParsingError, resulting in a warning being logged.
Move urllib3 to src/urllib3