Move from bullseye-slim to bookworm-slim

Also moves from bullseye in the processor to bullseye-slim. This requires
adding back the apt intall, yet the tests/docker cache should handle it.

Minimizes processor image surface, hopefully also shrinks the CI down a bit.

deploy/processor/Dockerfile

@@ -27,7 +27,7 @@ RUN --mount=type=cache,target=/root/.cargo \
   mv /serai/target/release/serai-processor /serai/bin
 
 # Prepare Image
-FROM debian:bullseye as image
+FROM debian:bookworm-slim as image
 LABEL description="STAGE 2: Copy and Run"
 
 WORKDIR /home/serai
@@ -36,5 +36,8 @@ WORKDIR /home/serai
 COPY --from=builder /serai/bin/* /bin/
 COPY --from=builder /serai/AGPL-3.0 .
 
+# Install openssl
+RUN apt update && apt upgrade -y && apt install -y libssl1.1
+
 # Run processor
 CMD ["serai-processor"]