try removing incremental build files to see if it helps ci disk usage

.drone.yml

@@ -16,6 +16,8 @@ steps:
     path: /drone/src/target
   commands:
   - cargo sweep --maxsize 12GiB
+  environment:
+    CARGO_INCREMENTAL: false
 - name: build
   image: rustlang/rust:nightly
   volumes:
@@ -25,6 +27,8 @@ steps:
     path: /drone/src/target
   commands:
   - cargo build
+  environment:
+    CARGO_INCREMENTAL: false
 - name: clippy!
   image: rustlang/rust:nightly
   volumes:
@@ -34,6 +38,8 @@ steps:
     path: /drone/src/target
   commands:
   - cargo clippy -- --deny warnings
+  environment:
+    CARGO_INCREMENTAL: false
 - name: test
   image: rustlang/rust:nightly
   volumes:
@@ -43,6 +49,8 @@ steps:
     path: /drone/src/target
   commands:
   - cargo test --jobs 1
+  environment:
+    CARGO_INCREMENTAL: false
 
 volumes:
 - name: cache