Pull request 1838: 5716-content-type

Updates #5716.

Squashed commit of the following:

commit 584e6771c82b92857e3c13232e942cad5c183682
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Wed Apr 19 14:54:43 2023 +0300

    all: fix content types

openapi/CHANGELOG.md

@@ -4,6 +4,16 @@
 
 ## v0.108.0: API changes
 
+## v0.107.30: API changes
+
+### `POST /control/version.json` and `GET /control/dhcp/interfaces` content type
+
+* The value of the `Content-Type` header in the `POST /control/version.json` and
+  `GET /control/dhcp/interfaces` HTTP APIs is now correctly set to
+  `application/json` as opposed to `text/plain`.
+
+
+
 ## v0.107.29: API changes
 
 ### `GET /control/clients` And `GET /control/clients/find`
@@ -16,6 +26,8 @@
   set AdGuard Home will use default value (false).  It can be changed in the
   future versions.
 
+
+
 ## v0.107.27: API changes
 
 ### The new optional fields `"edns_cs_use_custom"` and `"edns_cs_custom_ip"` in `DNSConfig`