Upgrade dmutils to 8.1.1
Upgrade dmutils to 8.1.1

This includes:
- alphagov/digitalmarketplace-utils#171
- alphagov/digitalmarketplace-utils#169
- alphagov/digitalmarketplace-utils#167
- alphagov/digitalmarketplace-utils#170
- alphagov/digitalmarketplace-utils#166
- alphagov/digitalmarketplace-utils#164
- alphagov/digitalmarketplace-utils#163
- alphagov/digitalmarketplace-utils#162
- alphagov/digitalmarketplace-utils#161
- alphagov/digitalmarketplace-utils#160
- alphagov/digitalmarketplace-utils#159
- alphagov/digitalmarketplace-utils#158
- alphagov/digitalmarketplace-utils#156
- alphagov/digitalmarketplace-utils#155
- alphagov/digitalmarketplace-utils#154
- alphagov/digitalmarketplace-utils#153

alphagov/digitalmarketplace-search-api,alphagov/digitalmarketplace-search-api