Remove unnecessary virtual specifiers

Clang has added a new warning for virtual specifiers on methods of
`final` classes. This cleans them up in preparation for enabling that
warning.

Bug: chromium:403236787
Change-Id: I1bb144494028f674d0de409a65412af1f084b56c
Reviewed-on: https://chromium-review.googlesource.com/c/openscreen/+/6391658
Commit-Queue: Mark Foltz <mfoltz@chromium.org>
Reviewed-by: Mark Foltz <mfoltz@chromium.org>

osp/public/service_listener.h

diff --git a/osp/public/service_listener.h b/osp/public/service_listener.h
index 3407ce9..9dbe1b2 100644
--- a/osp/public/service_listener.h
+++ b/osp/public/service_listener.h
@@ -96,7 +96,7 @@
   ServiceListener& operator=(const ServiceListener&) = delete;
   ServiceListener(ServiceListener&&) noexcept = delete;
   ServiceListener& operator=(ServiceListener&&) noexcept = delete;
-  virtual ~ServiceListener();
+  ~ServiceListener();
 
   // Sets the service configuration for this listener.
   void SetConfig(const Config& config);

osp/public/service_publisher.h

diff --git a/osp/public/service_publisher.h b/osp/public/service_publisher.h
index d231e2a..fdadc8a 100644
--- a/osp/public/service_publisher.h
+++ b/osp/public/service_publisher.h
@@ -103,7 +103,7 @@
   ServicePublisher& operator=(const ServicePublisher&) = delete;
   ServicePublisher(ServicePublisher&&) noexcept = delete;
   ServicePublisher& operator=(ServicePublisher&&) noexcept = delete;
-  virtual ~ServicePublisher();
+  ~ServicePublisher();
 
   // Sets the service configuration for this publisher.
   void SetConfig(const Config& config);