Revert "Use Qt 6.8.1 for arm64 Linux builds"

This reverts commit 1c22940.

Author: adazem009

.github/workflows/linux-build.yml

@@ -17,7 +17,7 @@ jobs:
             qt-target: 'desktop'
             qt-modules: ''
             arch: 'amd64'
-          - qt-version: '6.8.1'
+          - qt-version: '6.8'
             qt-target: 'desktop'
             qt-modules: 'qtshadertools'
             arch: 'aarch64'

.github/workflows/release.yml

@@ -14,7 +14,7 @@ jobs:
             qt-target: 'desktop'
             qt-modules: ''
             arch: 'amd64'
-          - qt-version: '6.8.1'
+          - qt-version: '6.8'
             qt-target: 'desktop'
             qt-modules: 'qtshadertools'
             arch: 'aarch64'