Bump plugin API

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Author: kugel-

src/plugindata.h

@@ -57,7 +57,7 @@ G_BEGIN_DECLS
  * @warning You should not test for values below 200 as previously
  * @c GEANY_API_VERSION was defined as an enum value, not a macro.
  */
-#define GEANY_API_VERSION 246
+#define GEANY_API_VERSION 247
 
 /* hack to have a different ABI when built with different GTK major versions
  * because loading plugins linked to a different one leads to crashes.