PHPC-1538: authSource in URI string no longer requires credentials (mongodb#1248)

Bump libmongoc 1.19.0 to pull in changes from CDRIVER-3502.

Unfortunately, the restriction is still in place for authSource in the URI options array (pending PHPC-1950).

Author: jmikola

src/LIBMONGOC_VERSION_CURRENT

@@ -1 +1 @@
-1.11.1-20210804+git230369cd07
+1.19.0

src/libmongoc

@@ -33,10 +33,7 @@ echo throws(function() {
     create_test_manager('mongodb://localhost:27017/', ['password' => 'password', 'authMechanism' => 'MONGODB-X509']);
 }, "MongoDB\Driver\Exception\InvalidArgumentException"), "\n";
 
-echo throws(function() {
-    create_test_manager('mongodb://localhost:27017/?authSource=foo');
-}, "MongoDB\Driver\Exception\InvalidArgumentException"), "\n";
-
+// TODO: This test case should be removed by PHPC-1950
 echo throws(function() {
     create_test_manager('mongodb://localhost:27017/', ['authSource' => 'foo']);
 }, "MongoDB\Driver\Exception\InvalidArgumentException"), "\n";
@@ -60,7 +57,5 @@ Failed to parse URI options: 'SCRAM-SHA-1' authentication mechanism requires use
 OK: Got MongoDB\Driver\Exception\InvalidArgumentException
 Failed to parse URI options: X509 authentication mechanism does not accept a password.
 OK: Got MongoDB\Driver\Exception\InvalidArgumentException
-Failed to parse MongoDB URI: 'mongodb://localhost:27017/?authSource=foo'. Default authentication mechanism requires username.
-OK: Got MongoDB\Driver\Exception\InvalidArgumentException
 Failed to parse URI options: Default authentication mechanism requires username.
 ===DONE===