build: change sed flags in installer for mac os compatibility

scripts/installer/installer

@@ -37,7 +37,7 @@ function install_abra_release {
   # FIXME: support different architectures
   PLATFORM=$(uname -s | tr '[:upper:]' '[:lower:]')_$(uname -m)
   sed_command='s/.*"assets":\[\{[^}]*"name":"abra.*_'"$PLATFORM"'"[^}]*"browser_download_url":"([^"]*)".*\].*/\1/p'
-  release_url=$(curl -s $ABRA_RELEASE_URL | sed -rn $sed_command -)
+  release_url=$(curl -s $ABRA_RELEASE_URL | sed -En $sed_command)
 
   echo "downloading $ABRA_VERSION $PLATFORM binary release for abra..."
   curl --progress-bar "$release_url" --output "$HOME/.local/bin/abra"