add Theme Berenice, a photo album theme

Author: 22decembre

themes.txt

@@ -2,6 +2,7 @@ codeberg.org/gbilder/eurozephyr
 github.com/10mohi6/hugo-theme-simple-blog
 github.com/1bl4z3r/hermit-V2
 github.com/2-REC/hugo-myportfolio-theme
+github.com/22decembre/Berenice
 github.com/526avijitgupta/gokarna
 github.com/64bitpandas/amethyst
 github.com/7ma7X/HugoTeX