fix: Explicitly set TLS backends

Dependency updates mean we have to set a custom TLS backend sooner.
Also some groundwork for being able to use aws-lc in future

docker/Dockerfile

@@ -162,7 +162,7 @@ ENV CONDUWUIT_VERSION_EXTRA=$CONDUWUIT_VERSION_EXTRA
 ENV CONTINUWUITY_VERSION_EXTRA=$CONTINUWUITY_VERSION_EXTRA
 
 ARG RUST_PROFILE=release
-ARG CARGO_FEATURES="default,http3"
+ARG CARGO_FEATURES="default"
 
 # Build the binary
 RUN --mount=type=cache,target=/usr/local/cargo/registry \