ci: Support for arm64 docker builds

Dockerfile.arm64

@@ -0,0 +1,27 @@
+FROM messense/rust-musl-cross:armv7-musleabihf AS builder
+WORKDIR /usr/src
+
+# Download and compile Rust dependencies in an empty project and cache as a separate Docker layer
+RUN USER=root cargo new --bin managarr-temp
+RUN apt update && apt install -y libssl-dev pkg-config
+
+WORKDIR /usr/src/managarr-temp
+COPY Cargo.* .
+RUN cargo build --release
+# remove src from empty project
+RUN rm -r src
+COPY src ./src
+# remove previous deps
+RUN rm ./target/armv7-unknown-linux-musleabihf/release/deps/managarr*
+
+RUN --mount=type=cache,target=/volume/target \
+    --mount=type=cache,target=/root/.cargo/registry \
+    cargo build --release --bin managarr
+RUN mv target/armv7-unknown-linux-musleabihf/release/managarr .
+
+FROM debian:stable-slim
+
+# Copy the compiled binary from the builder container
+COPY --from=builder --chown=nonroot:nonroot /usr/src/managarr-temp/managarr /usr/local/bin
+
+ENTRYPOINT [ "/usr/local/bin/managarr" ]