fix(dockerfile): update Railpack installation script to use bash

Author: Siumauricio

Dockerfile

@@ -57,7 +57,7 @@ RUN curl -sSL https://nixpacks.com/install.sh -o install.sh \
 
 # Install Railpack
 ARG RAILPACK_VERSION=0.0.37
-RUN curl -sSL https://railpack.com/install.sh | sh
+RUN curl -sSL https://railpack.com/install.sh | bash
 
 # Install buildpacks
 COPY --from=buildpacksio/pack:0.35.0 /usr/local/bin/pack /usr/local/bin/pack