Fix the problem connected with marked date range

Author: ManukMinasyan

package.json

@@ -6,7 +6,7 @@
   },
   "name": "vue-functional-calendar",
   "description": "A style-uninstallable datepicker component for Vue.js",
-  "version": "2.3.0",
+  "version": "2.3.1",
   "license": "MIT",
   "repository": {
     "type": "git",

src/components/FunctionalCalendar.vue

@@ -711,10 +711,10 @@
                 return classes;
             },
             checkDateRangeStart(date) {
-                return date === date === this.fConfigs.markedDateRange.start;
+                return date === this.fConfigs.markedDateRange.start;
             },
             checkDateRangeEnd(date) {
-                return date === date === this.fConfigs.markedDateRange.end;
+                return date === this.fConfigs.markedDateRange.end;
             },
             getTransition_() {
                 if (!this.fConfigs.transition)