build: update MSRV in Dockerfile

Author: mbhall88

Dockerfile

@@ -1,4 +1,4 @@
-FROM rust:1.55 AS builder
+FROM rust:1.81.0 AS builder
 
 COPY . /psdm
 
@@ -20,4 +20,4 @@ COPY --from=builder /psdm/target/${TARGET}/release/psdm /bin/
 
 RUN psdm --version
 
-ENTRYPOINT [ "/bin/bash", "-l", "-c" ]
+ENTRYPOINT [ "/bin/bash", "-l", "-c" ]