builds: check code style

.builds/alpine.yml

@@ -2,6 +2,7 @@
 image: alpine/edge
 packages:
   - clang
+  - clang-extra-tools
   - gcc
 sources:
   - "https://git.sr.ht/~jeremy/callisto"
@@ -19,3 +20,7 @@ tasks:
       sudo make -Ccallisto install
   - test: |
       csto callisto/test.lua
+  - format: |
+      cd callisto
+      make format
+      git diff --exit-code

.builds/archlinux.yml

@@ -24,5 +24,9 @@ tasks:
       sudo make -Ccallisto install
   - test: |
       csto callisto/test.lua
+  - format: |
+      cd callisto
+      make format
+      git diff --exit-code
   - flake: |
       nix build ./callisto