Allow line length up to 100char

Same as we have for Ruby code: https://github.com/openfoodfoundation/openfoodnetwork/blob/master/.rubocop_styleguide.yml#L78-L80

This will avoid unnecessary reformatting.

.prettierrc.json

@@ -1 +1,3 @@
-{}
+{
+  "printWidth": 100
+}