bump utils to 89.1.0

we need to update the makefile bootstrap command, as this version moves
to using pip-tools to lock requirements based on a .in file.

The bootstrap command does the following in order:

* install requirements.txt first to get the latest version of utils
* Copy the shared reqs files from the new utils into the local repo
* compile those shared reqs into a requirements_for_test.txt lockfile
* Actually install the test requirements

Makefile

@@ -9,6 +9,8 @@ help:
 bootstrap: ## Install build dependencies
 	pip install -r requirements.txt
 	python -c "from notifications_utils.version_tools import copy_config; copy_config()"
+	pip install --upgrade pip-tools
+	pip-compile requirements_for_test.in
 	pip install -r requirements_for_test.txt
 
 .PHONY: build

requirements.txt

@@ -4,4 +4,4 @@
 # it to work out the current utils version
 
 # Run `make bump-utils` to update to the latest version
-notifications-utils @ git+https://github.com/alphagov/notifications-utils.git@82.1.2
+notifications-utils @ git+https://github.com/alphagov/notifications-utils.git@89.1.0