Fix CI image generation, make build verbose

Apparently, `cargo` doesn't notice that the main.rs file changed with
the COPY.

Dockerfile

@@ -17,7 +17,8 @@ RUN RUSTFLAGS=-Clinker=musl-gcc cargo build --release --target=x86_64-unknown-li
 COPY src/ src/
 
 RUN rm -f target/x86_64-unknown-linux-musl/release/deps/mittelab-status* \
-    && RUSTFLAGS=-Clinker=musl-gcc cargo build --release --target=x86_64-unknown-linux-musl
+    && touch src/main.rs \
+    && RUSTFLAGS=-Clinker=musl-gcc cargo build --verbose --release --target=x86_64-unknown-linux-musl
 
 # ------------------------------------------------------------------------------
 # Final Stage