If CentOS does not have that version in the repos (and CentOS usually doesn't have bleeding edge), you will likely have to
compile from sources.
It's possible that you might find an RPM from a different distro, but RPMs from one distro are often not compatible with other distros; that's what gave birth to the term,
RPM hell.
It's really not all that difficult, but you should check the dependencies. It's possible that the latest Pidgin version requires some newer libraries than the one you have currently.
If you are missing any dependencies, the configure step (see the link on compiling) will throw errors that tell you what's missing, so you can track it down. Note that the dependencies may also have dependencies that you will need to satisfy.
Update pidgin to latest version
