Multiline UDAs broken

Multiline string UDAs, which worked fine in TaskWarrior 2.5.3 with the addition of #2132 are now broken in latest release:

```
[:~/git/vit] 2.x+ ± task 1 modify notes:"one"
Modifying task 1 'test'.
Modified 1 task.
TASKRC override: /tmp/tmp.XCtk4fQYjA.vit/taskrc
[:~/git/vit] 2.x+ ± task 1
TASKRC override: /tmp/tmp.XCtk4fQYjA.vit/taskrc

Name Value
ID 1
Description test
Status Pending
Entered 2021-10-11 (Mon) (15min)
Last modified 2021-10-11 (Mon) (2s)
Virtual tags PENDING READY UDA UNBLOCKED
UUID a5e07137-2ecb-4372-9e89-422e11aa9068
Urgency 0
Notes one

[:~/git/vit] 2.x+ ± task 1 modify notes:"two
$
$three"
Modifying task 1 'notes:two

three'.
Modified 1 task.
TASKRC override: /tmp/tmp.XCtk4fQYjA.vit/taskrc
[:~/git/vit] 2.x+ ± task 1
TASKRC override: /tmp/tmp.XCtk4fQYjA.vit/taskrc

Name Value
ID 1
Description notes:two

three
Status Pending
Entered 2021-10-11 (Mon) (15min)
Last modified 2021-10-11 (Mon) (2s)
Virtual tags PENDING READY UDA UNBLOCKED
UUID a5e07137-2ecb-4372-9e89-422e11aa9068
Urgency 0
Notes one
```

Possibly related to #2283 ?