the: log a debug only when text is changed
the: log a debug only when text is changed

Previously the `the` plugin would log a debug message when the text _didn't_ get changed by the plugin, whereas I think what was intended was the opposite. With this change the logged messages show the actual transformations made by the plugin.
beetbox/beets,shamangeorge/beets,jackwilsdon/beets,jackwilsdon/beets,SusannaMaria/beets,beetbox/beets,SusannaMaria/beets,sampsyo/beets,ibmibmibm/beets,ibmibmibm/beets,beetbox/beets,ibmibmibm/beets,shamangeorge/beets,ibmibmibm/beets,SusannaMaria/beets,jackwilsdon/beets,beetbox/beets,sampsyo/beets,shamangeorge/beets,shamangeorge/beets,sampsyo/beets,jackwilsdon/beets,SusannaMaria/beets,sampsyo/beets