workflows: Define a zephyr tag

Signed-off-by: Dhruva Gole <41233856+DhruvaG2000@users.noreply.github.com>

Author: DhruvaG2000

.github/workflows/build.yml

@@ -5,7 +5,7 @@ on: [push, pull_request]
 jobs:
   build:
     runs-on: ubuntu-latest
-    container: zephyrprojectrtos/ci:latest
+    container: zephyrprojectrtos/zephyr-build:v0.26.13
     env:
       CMAKE_PREFIX_PATH: /opt/toolchains
     steps: