gha: restrict cross and bin-image to 20 minutes

We had a couple of runs where these jobs got stuck and github
actions didn't allow terminating them, so that they were only
terminated after 120 minutes.

These jobs usually complete in 5 minutes, so let's give them
a shorter timeout. 20 minutes should be enough (don't @ me).

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

.github/workflows/bin-image.yml

@@ -41,7 +41,7 @@ jobs:
 
   prepare:
     runs-on: ubuntu-20.04
-    timeout-minutes: 120 # guardrails timeout for the whole job
+    timeout-minutes: 20 # guardrails timeout for the whole job
     outputs:
       platforms: ${{ steps.platforms.outputs.matrix }}
     steps:

.github/workflows/ci.yml

@@ -70,7 +70,7 @@ jobs:
 
   prepare-cross:
     runs-on: ubuntu-latest
-    timeout-minutes: 120 # guardrails timeout for the whole job
+    timeout-minutes: 20 # guardrails timeout for the whole job
     needs:
       - validate-dco
     outputs:
@@ -92,7 +92,7 @@ jobs:
 
   cross:
     runs-on: ubuntu-20.04
-    timeout-minutes: 120 # guardrails timeout for the whole job
+    timeout-minutes: 20 # guardrails timeout for the whole job
     needs:
       - validate-dco
       - prepare-cross