add validation on decimal max 3 digits after coma

app/models/champs/decimal_number_champ.rb

@@ -1,6 +1,14 @@
 class Champs::DecimalNumberChamp < Champ
   before_validation :format_value
-  validates :value, numericality: {
+  validates :value, format: {
+    with: /\A-?[0-9]+([\.,][0-9]{1,3})?\z/,
+    allow_nil: true,
+    allow_blank: true,
+    message: -> (object, _data) {
+      # i18n-tasks-use t('errors.messages.not_a_float')
+      "« #{object.libelle} » " + object.errors.generate_message(:value, :not_a_float)
+    }
+  }, numericality: {
     allow_nil: true,
     allow_blank: true,
     message: -> (object, _data) {