Bump popper.js to 1.12.9

Author: beenje

flask_bootstrap/__init__.py

@@ -21,7 +21,7 @@ def is_hidden_field_filter(field):
 
 __version__ = '4.0.0-beta.0.dev1'
 BOOTSTRAP_VERSION_RE = re.compile(r'(\d+\.\d+\.\d+(\-[a-z]+)?)')
-POPPER_VERSION = '1.11.1'
+POPPER_VERSION = '1.12.9'
 JQUERY_VERSION = '3.2.1'