fix: translate months in gantt chart

Related to #774

src/components/tasks/gantt-component.vue

@@ -194,7 +194,6 @@ import TaskCollectionService from '../../services/taskCollection'
 import {mapState} from 'vuex'
 import Rights from '../../models/constants/rights.json'
 import FilterPopup from '@/components/list/partials/filter-popup.vue'
-import {format} from 'date-fns'
 
 export default {
 	name: 'GanttChart',
@@ -474,7 +473,7 @@ export default {
 				})
 		},
 		formatYear(date) {
-			return format(date, 'MMMM, yyyy')
+			return this.format(date, 'MMMM, yyyy')
 		},
 	},
 }

src/main.ts

@@ -112,6 +112,9 @@ Vue.mixin({
 		formatDateShort(date) {
 			return formatDate(date, 'PPpp', this.$t('date.locale'))
 		},
+		format(date, f) {
+			return formatDate(date, f, this.$t('date.locale'))
+		},
 		getNamespaceTitle(n) {
 			return getNamespaceTitle(n, (p: VueI18n.Path) => this.$t(p))
 		},