ext: Checkout libaom v3.0.0

Updates the libaom version checked out in the ext and docker scripts from v2.0.0 to v3.0.0
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 38e32be..545a9b9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,10 @@
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+
+### Changed
+* Update aom.cmd: v3.0.0
 
 ## [0.9.0] - 2021-02-22
 
diff --git a/ext/aom.cmd b/ext/aom.cmd
index 789df67..39d20c9 100755
--- a/ext/aom.cmd
+++ b/ext/aom.cmd
@@ -8,7 +8,7 @@
 : # If you're running this on Windows, be sure you've already run this (from your VC2019 install dir):
 : #     "C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\VC\Auxiliary\Build\vcvars64.bat"
 
-git clone -b v2.0.2 --depth 1 https://aomedia.googlesource.com/aom
+git clone -b v3.0.0 --depth 1 https://aomedia.googlesource.com/aom
 
 cd aom
 mkdir build.libavif
diff --git a/tests/docker/build.sh b/tests/docker/build.sh
index fca772d..a563c7a 100644
--- a/tests/docker/build.sh
+++ b/tests/docker/build.sh
@@ -34,7 +34,7 @@
 
 # aom
 cd
-git clone -b v2.0.2 --depth 1 https://aomedia.googlesource.com/aom
+git clone -b v3.0.0 --depth 1 https://aomedia.googlesource.com/aom
 cd aom
 mkdir build.avif
 cd build.avif