Fix build error

.build.yml

@@ -1,17 +1,12 @@
-image: debian/stable
+image: alpine/edge
 packages:
-    - curl
+    - rust 
+    - cargo
 
 sources:
   - https://git.sr.ht/~victormignot/yorokobot
 
 tasks:
-  - setup: |
-      curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -y
-      rustup toolchain install stable
-      rustup default stable
-      source $HOME/.cargo/env
-
   - format-check: |
       cd yorokobot
       cargo fmt --check