scripts/install-buildtools: Update to 4.0.21

Update to the 4.0.21 release of the 4.0 series for buildtools.

(From OE-Core rev: e6170a6c9ea419d2fdc4e4ceb04c8a399b4a3b43)

Signed-off-by: Aleksandar Nikolic <aleksandar.nikolic@zeiss.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

scripts/install-buildtools

@@ -56,9 +56,9 @@ PROGNAME = 'install-buildtools'
 logger = scriptutils.logger_create(PROGNAME, stream=sys.stdout)
 
 DEFAULT_INSTALL_DIR = os.path.join(os.path.split(scripts_path)[0],'buildtools')
-DEFAULT_BASE_URL = 'http://downloads.yoctoproject.org/releases/yocto'
-DEFAULT_RELEASE = 'yocto-4.1'
-DEFAULT_INSTALLER_VERSION = '4.1'
+DEFAULT_BASE_URL = 'https://downloads.yoctoproject.org/releases/yocto'
+DEFAULT_RELEASE = 'yocto-4.0.21'
+DEFAULT_INSTALLER_VERSION = '4.0.21'
 DEFAULT_BUILDDATE = '202110XX'
 
 # Python version sanity check