Prepare v0.7.0-dev.2021080801 releases

[daohoangson]

No description provided.

[github-actions]

Demo app

Deployed 8711630 to https://example-5vd7dj5p2-flutter-widget-from-html.vercel.app.

Quick links:

• supported/tags.html
• Hello World
• Hello World (core)
• Wordpress
• --web-renderer canvaskit
• --web-renderer html

[codecov]

Codecov Report

Merging #560 (b17c5bd) into next (f0cd0eb) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             next     #560   +/-   ##
=======================================
  Coverage   98.19%   98.19%           
=======================================
  Files          49       49           
  Lines        3153     3153           
=======================================
  Hits         3096     3096           
  Misses         57       57           

Impacted Files	Coverage Δ
packages/core/lib/src/core_html_widget.dart	100.00% <ø> (ø)

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