fix(web): locked_cached_property import error

Fix flask.helpers locked_cached_property import error that has been
removed in recent versions of Flask. The upstream changed is tracked in
this PR:

pallets/flask#4998

According to Flask upstream developers, the right solution is to used
cached_property from werkzeug.utils instead.

fix #190

Author: rezib

CHANGELOG.md

@@ -259,6 +259,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Drop off artifact and sources archives tarballs in subdirectory of fatbuildr
   runtime directory to avoid potential collisions between multiple builds in
   queue (#179).
+- Fix `flask.helpers` `locked_cached_property` import error in recent versions
+  of Flask (#190).
 - docs:
   - Add missing path parameter in REST API to retrieve artifact information.
   - Add missing optional `architectures` parameter in instances pipelines

fatbuildr/protocols/http/server/__init__.py

@@ -21,7 +21,7 @@
 from pathlib import Path
 
 from flask import Flask
-from flask.helpers import locked_cached_property
+from werkzeug.utils import cached_property
 from jinja2 import FileSystemLoader
 
 from . import views
@@ -219,7 +219,7 @@ def run(self):
             debug=self.conf.run.debug,
         )
 
-    @locked_cached_property
+    @cached_property
     def jinja_loader(self):
         """Override Flask Scaffold.jinja_loader() to use Jinja2
         FileSystemLoader with 2 paths: the site templates directory and the