ci: use /etc/os-release instead of lsb_release

.gitea/workflows/ci.yml

@@ -40,7 +40,8 @@ jobs:
       - name: Install Nomad CLI
         run: |
           curl -fsSL https://apt.releases.hashicorp.com/gpg | gpg --dearmor -o /usr/share/keyrings/hashicorp.gpg
-          echo "deb [signed-by=/usr/share/keyrings/hashicorp.gpg] https://apt.releases.hashicorp.com $(lsb_release -cs) main" | tee /etc/apt/sources.list.d/hashicorp.list
+          . /etc/os-release
+          echo "deb [signed-by=/usr/share/keyrings/hashicorp.gpg] https://apt.releases.hashicorp.com ${VERSION_CODENAME} main" | tee /etc/apt/sources.list.d/hashicorp.list
           apt-get update && apt-get install -y nomad
 
       - name: Validate all job specs