Fix logo in README not being visible in high-contrast mode. Fix #8160

Co-authored-by: Thibaud Colas <thibaudcolas@gmail.com>

CHANGELOG.txt

@@ -38,6 +38,7 @@ Changelog
  * Docs: Mention Wagtail’s usage of Django’s default user model by default (Temidayo Azeez)
  * Docs: Add links to treebeard documentation for relevant methods (Temidayo Azeez)
  * Docs: Add clarification on where to register entity plugins (ChickenF622)
+ * Docs: Fix logo in README not being visible in high-contrast mode (Benita Anawonah)
  * Maintenance: Remove unsquashed `testapp` migrations (Matt Westcott)
  * Maintenance: Upgrade to Node 18 for frontend build tooling (LB (Ben) Johnston)
  * Maintenance: Run Python tests with coverage and upload coverage data to codecov (Sage Abdullah)

CONTRIBUTORS.rst

@@ -669,6 +669,7 @@ Contributors
 * Suyash Singh
 * Temidayo Azeez
 * ChickenF622
+* Benita Anawonah
 
 Translators
 ===========

docs/releases/4.2.md

@@ -54,6 +54,7 @@ depth: 1
  * Mention Wagtail’s usage of Django’s default user model by default (Temidayo Azeez)
  * Add links to treebeard documentation for relevant methods (Temidayo Azeez)
  * Add clarification on where to register entity plugins (ChickenF622)
+ * Fix logo in README not being visible in high-contrast mode (Benita Anawonah)
 
 ### Maintenance