Add a dockerfile for docker deployments

Signed-off-by: baalajimaestro <me@baalajimaestro.me>

Dockerfile

@@ -0,0 +1,15 @@
+FROM rust:bullseye as builder
+
+RUN mkdir /app
+
+COPY src /app/src
+COPY Cargo.toml /app
+WORKDIR /app
+RUN cargo build --release
+
+FROM gcr.io/distroless/cc:latest
+
+COPY --from=builder /app/target/release/mail-deleter /
+VOLUME /patterns.txt
+
+CMD ["./mail-deleter"]