ci: enable target x86_64-unknown-linux-gnux32

Author: xtqqczze

.github/workflows/ci.yaml

@@ -238,8 +238,7 @@ jobs:
           - target: x86_64-linux-android
             # Keep in sync with the Android build pinned in ci/cuttlefish-setup.sh
             artifact-tag: android17
-          # FIXME: Exec format error (os error 8)
-          # - target: x86_64-unknown-linux-gnux32
+          - target: x86_64-unknown-linux-gnux32
           - target: x86_64-unknown-linux-musl
           - target: x86_64-unknown-linux-musl
             env: { TEST_MUSL_V1_2_3: 1 }