feat: only update toolchain if it is 'nightly'

entrypoint.sh

@@ -15,6 +15,8 @@ echo "Default toolchain: ${TOOLCHAIN}"
 if test "${ARGS[0]}" == "nightly"; then
   TOOLCHAIN="nightly"
   ARGS=("${ARGS[@]:1}")
+  echo ">>> Update nightly toolchain"
+  rustup update "${TOOLCHAIN}"
 fi
 if test "${ARGS[0]}" == "stable"; then
   TOOLCHAIN="stable" # redundant as this is the default
@@ -26,8 +28,6 @@ if [[ "${ARGS[0]}" == v1* ]]; then
 fi
 echo "Selected toolchain: ${TOOLCHAIN}"
 
-echo ">>> Update toolchain"
-rustup update "${TOOLCHAIN}"
 echo ">>> Install rustfmt and clippy"
 rustup component add --toolchain "${TOOLCHAIN}" rustfmt clippy