Fix API requests content type

src_assets/common/assets/web/apps.html

@@ -735,6 +735,9 @@
           this.actionDisabled = true;
           fetch("./api/apps/close", {
             credentials: 'include',
+            headers: {
+              'Content-Type': 'application/json'
+            },
             method: 'POST',
           })
           .then((r) => r.json())

src_assets/common/assets/web/config.html

@@ -475,7 +475,10 @@
               this.saved = this.restarted = false;
             }, 5000);
             fetch("./api/restart", {
-              method: 'POST'
+              method: 'POST',
+              headers: {
+                'Content-Type': 'application/json'
+              }
             })
             .then((resp) => {
               if (resp.status !== 200) {

src_assets/common/assets/web/pin.html

@@ -655,7 +655,10 @@
         this.unpairAllPressed = true;
         fetch("./api/clients/unpair-all", {
           credentials: 'include',
-          method: 'POST'
+          method: 'POST',
+          headers: {
+            'Content-Type': 'application/json'
+          },
         })
           .then((r) => r.json())
           .then((r) => {