build: fix snapshot linux version

Author: Bogdanp

build.sh

@@ -51,10 +51,10 @@ installer_url () {
 build_snapshot () {
   declare -r version="snapshot";
 
-  declare -r installer="https://users.cs.utah.edu/plt/snapshots/current/installers/racket-minimal-current-x86_64-linux-jesse.sh";
+  declare -r installer="https://users.cs.utah.edu/plt/snapshots/current/installers/racket-minimal-current-x86_64-linux-buster.sh";
   build "racket" "${installer}" "${version}" "${version}";
 
-  declare -r full_installer="https://users.cs.utah.edu/plt/snapshots/current/installers/racket-current-x86_64-linux-jesse.sh";
+  declare -r full_installer="https://users.cs.utah.edu/plt/snapshots/current/installers/racket-current-x86_64-linux-buster.sh";
   build "racket" "${full_installer}" "${version}" "${version}-full";
 }