fix: use .d.ts instead of .vue.d.ts for Vue declarations (#336)

* - fix for vue declaration file names

* fix: use .d.ts instead of .vue.d.ts for Vue declarations

- `.vue.d.ts` was recommended by the `rollup-plugin-vue` maintainers
  back when this code was originally written, but apparently it causes
  problems with some imports
  - plain `.d.ts` seems to work fine according to users
    - and plain is the standard in TS too I believe

Co-authored-by: ezolenko <[email protected]>

src/index.ts

@@ -328,7 +328,7 @@ const typescript: PluginImpl<RPT2Options> = (options) =>
 
 				let fileName = entry.name;
 				if (fileName.includes("?")) // HACK for rollup-plugin-vue, it creates virtual modules in form 'file.vue?rollup-plugin-vue=script.ts'
-					fileName = fileName.split("?", 1) + extension;
+					fileName = fileName.split(".vue?", 1) + extension;
 
 				// If 'useTsconfigDeclarationDir' is given in the
 				// plugin options, directly write to the path provided