Use BUNDLE_FORCE_RUBY_PLATFORM=1 + further update.sh improvements

pkgs/applications/editors/jupyter-kernels/iruby/update.sh

@@ -1,4 +1,5 @@
-#!/usr/bin/env bash
+#! /usr/bin/env nix-shell
+#! nix-shell -i bash -p curl jq bundler bundix ruby
 
 set -eu -o pipefail
 
@@ -7,10 +8,11 @@ cd "$(dirname "$0")"
 # Update Gemfile with the latest iruby version
 echo "source 'https://rubygems.org'" > Gemfile
 echo -n "gem 'iruby', " >> Gemfile
-nix shell .#curl -c curl https://rubygems.org/api/v1/gems/iruby.json | nix shell .#jq -c jq .version >> Gemfile
+curl https://rubygems.org/api/v1/gems/iruby.json | jq .version >> Gemfile
 
 # Regenerate Gemfile.lock
-nix shell .#bundler -c bundle lock
+export BUNDLE_FORCE_RUBY_PLATFORM=1
+bundle lock
 
 # Regenerate gemset.nix
-nix shell .#bundix -c bundix -l
+bundix -l