update g:vimwiki_version for latest release

I missed this before tagging; this will be v2023.04.04_1.

plugin/vimwiki.vim

@@ -11,7 +11,7 @@ endif
 let g:loaded_vimwiki = 1
 
 " Set to version number for release:
-let g:vimwiki_version = '2022.12.02'
+let g:vimwiki_version = '2023.04.04'
 
 " Get the directory the script is installed in
 let s:plugin_dir = expand('<sfile>:p:h:h')

test/tag.vader

@@ -257,7 +257,7 @@ Expect (Correctly formatted tags file):
   !_TAG_PROGRAM_AUTHOR	Vimwiki
   !_TAG_PROGRAM_NAME	Vimwiki Tags
   !_TAG_PROGRAM_URL	https://github.com/vimwiki/vimwiki
-  !_TAG_PROGRAM_VERSION	2022.12.02
+  !_TAG_PROGRAM_VERSION	2023.04.04
   second-tag	Test-Tag.md	13;"	vimwiki:Test-Tag\tTest-Tag#second-tag\tTest-Tag#second-tag
   test-tag	Test-Tag.md	5;"	vimwiki:Test-Tag\tTest-Tag#a-header\tA header
   top-tag	Test-Tag.md	1;"	vimwiki:Test-Tag\tTest-Tag\tTest-Tag