d/rules: Use debhelper 13 and standard dh sequence (Closes: #1101461)
CDBS has been deprecated by the upstream authors in 2021 and has been orphaned in 2022. [1]
The current packaging already relies on debhelper, so the conversion is quite straightforward and brings additional benefits like binary reproducibility fixes or support for any future infrastructural change.
diffoscope shows that the content of the main package is identical to
the existing package with the exception of an additional version
specification in shlibs:
@@ -1 +1 @@
-libreplaygain 1 libreplaygain1
+libreplaygain 1 libreplaygain1 (>= 1.0~r475)