Remove geocoder and geocoding script

We no longer use geocoded addresses on the site, so this dependency
can be removed.

scripts/geocode_coop_addresses.rb

@@ -1,21 +0,0 @@
-require 'bundler/setup'
-require 'yaml'
-require 'geocoder'
-
-Geocoder.configure(lookup: :nominatim)
-
-root_path = Pathname.new(__dir__).join('..')
-
-Dir[root_path.join('_coops/*.md')].each do |path|
-  content = File.read(path)
-  body = content.split("\n").reverse.take_while { |l| l != "---" }.reverse.join("\n")
-  metadata = YAML.safe_load(content)
-
-  address = metadata['address']
-  latitude, longitude = Geocoder.coordinates(address, params: { region: 'uk' })
-  metadata['latitude'] ||= latitude
-  metadata['longitude'] ||= longitude
-
-  frontmatter = YAML.dump(metadata)
-  File.write(path, frontmatter + "---" + "\n" + body)
-end