Use https protocol for git

Github has dropped support for git protocol.

Author: blowekamp

CMakeLists.txt

@@ -125,7 +125,7 @@ if(SimpleITKPythonPackage_SUPERBUILD)
         -DSimpleITK_INSTALL_DOC_DIR:STRING=SimpleITK
         -DSimpleITK_BUILD_STRIP:BOOL=ON
         -DSimpleITK_BUILD_DISTRIBUTE:BOOL=ON
-        -DSimpleITK_GIT_PROTOCOL:STRING=git
+        -DSimpleITK_GIT_PROTOCOL:STRING=https
         -DSKBUILD:BOOL=${SKBUILD}
       USES_TERMINAL_CONFIGURE 1
       USES_TERMINAL_BUILD 1