Use Cargo Sparse protocol in Docker build

Cargo 1.68 and newer introduced "sparse" protocol which significantly reduces memory usage (and improves build time!) - see https://blog.rust-lang.org/inside-rust/2023/01/30/cargo-sparse-protocol.html

Had to bump Alpine to 3.18 to pick up a more recent Cargo release (1.76.0)

hexpm/elixir do not sure Alpine 3.19 with current erlang+elixir combination

Dockerfile

@@ -1,4 +1,4 @@
-ARG ALPINE_VERSION=3.17.0
+ARG ALPINE_VERSION=3.18.0
 ARG ERLANG_OTP_VERSION=25.2.2
 ARG ELIXIR_VERSION=1.14.3
 
@@ -9,6 +9,9 @@ FROM docker.io/hexpm/elixir:${ELIXIR_VERSION}-erlang-${ERLANG_OTP_VERSION}-alpin
 
 ARG MIX_ENV=prod
 ENV ERL_FLAGS="+JPperf true"
+# Avoid "error 137" (out of memory) while building images
+# See https://github.com/rust-lang/cargo/issues/10781
+ENV CARGO_REGISTRIES_CRATES_IO_PROTOCOL="sparse"
 
 WORKDIR /opt/app