Update for v2.9 release

* Also fix GitHub Actions 404 errors when running apt install (See actions/runner-images#2924)

Author: pbatard

.github/workflows/build.yml

@@ -19,7 +19,9 @@ jobs:
       id: set_version
       run: echo "version=$(git describe --tags --abbrev=0)" >> $GITHUB_OUTPUT
     - name: Set up Linux environment
-      run: sudo apt install gcc-aarch64-linux-gnu
+      run: |
+        sudo apt-get update
+        sudo apt-get install gcc-aarch64-linux-gnu
     - name: Download and extract TF-A release
       run: |
         curl -L https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/snapshot/trusted-firmware-a-${{steps.set_version.outputs.version}}.tar.gz -o trusted-firmware-a-${{steps.set_version.outputs.version}}.tar.gz

Readme.md

@@ -17,7 +17,7 @@ altered from the ones one would build locally using the official TF-A source.
 
 # Current version
 
-The version of TF-A being built is 2.8, which was released on 2022-11-21.
+The version of TF-A being built is 2.9, which was released on 2023-05-23.
 
 # Binary validation