Update rust version in docker

Author: kenkoooo

atcoder-problems-backend/Dockerfile

@@ -1,4 +1,4 @@
-FROM rust:1.50.0 AS builder
+FROM rust:1.57.0 AS builder
 
 WORKDIR /app
 
@@ -25,7 +25,7 @@ ADD ./atcoder-client ./atcoder-client
 RUN cargo clean --release -p atcoder-client -p sql-client
 RUN cargo build --release
 
-FROM rust:1.50.0
+FROM rust:1.57.0
 COPY --from=builder /app/target/release/batch_update                /usr/bin/batch_update
 COPY --from=builder /app/target/release/crawl_all_submissions       /usr/bin/crawl_all_submissions
 COPY --from=builder /app/target/release/crawl_for_virtual_contests  /usr/bin/crawl_for_virtual_contests