github: pin docker workflows to ubuntu-24.04

Otherwise ubuntu-latest can sometimes still install ubuntu 22.04 which
becomes problematic when combined with
eabec52 ("github: install setuptools_scm via apt") due to differing
package versions.

Signed-off-by: Bastian Krause <bst@pengutronix.de>

Author: Bastian-Krause

.github/workflows/docker.yml

@@ -16,7 +16,7 @@ env:
 
 jobs:
   docker:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
     - uses: actions/checkout@v4
     - name: Install system dependencies

.github/workflows/reusable-unit-tests-docker.yml

@@ -9,7 +9,7 @@ on:
 
 jobs:
   docker:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
     - uses: actions/checkout@v4
       with: