Bump flask-assets from 0.12 to 2.0

[dependabot-preview]

Bumps flask-assets from 0.12 to 2.0.

Changelog

Sourced from flask-assets's changelog.

2.0 (2019-12-20) - Compatibility with webassets 2.0.

Commits

• 8d9a4e8 Update version.
• 450cac1 Add releasing notes.
• e9c36a3 Add funding.yml.
• 3cd7878 Merge pull request #129 from DuncanBetts/DuncanBetts-patch-1
• 5f8d13b Tiny typo
• ea9ff98 "Merge pull request #119 from brandones/master\n\nAdd section on Google App E...
• 19e3ff1 Add section on Google App Engine to the documentation
• 83d7d3a "Merge pull request #117 from pmlandwehr/master\n\n#coding: utf8 -> #coding: ...
• 9906bdd #coding: utf8 -> #coding: utf-8
• 6bdd973 Fix 0.12 release date in CHANGES.
• See full diff in compare view

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