Acrylic Paint: update repository URL to Phabricator

Since a couple of years the main repository of Acrylic Paint is
the one at gitpull.it and not on GitHub.

This can be verified visiting the legacy official repository:
	https://github.com/valerio-bozzolan/AcrylicPaint

And looking at the URL at the right sidebar quoting "gitpull.it".

The issue tracker will be migrated also soon but not now because
people still use GitHub.

Anyway, the current maintainer do not trust GitHub, so that's why
the source code is hosted elsewhere on the personal infrastructure
of the current maintainer.

metadata/anupam.acrylic.yml

@@ -1,7 +1,7 @@
 Categories:
   - Graphics
 License: GPL-3.0-or-later
-SourceCode: https://github.com/valerio-bozzolan/AcrylicPaint
+SourceCode: https://gitpull.it/source/acrylic-paint/
 IssueTracker: https://github.com/valerio-bozzolan/AcrylicPaint/issues
 
 AutoName: Acrylic Paint
@@ -9,12 +9,8 @@ Description: |-
     Acrylic Paint is a coloring tool based on the FingerPaint project taken from API
     demos.
 
-    We use a patched fork authorized by the
-    <a href="https://github.com/anupam1525/AcrylicPaint/">original author</a> until main
-    development is active again.
-
 RepoType: git
-Repo: https://github.com/valerio-bozzolan/AcrylicPaint.git
+Repo: https://gitpull.it/source/acrylic-paint/
 
 Builds:
   - versionName: 1.2.0