docs: Drop package_ver_str from include path

We add this in the pkg-config file so no need to specify it again.
3 jobs for doc-fixes in 7 minutes and 17 seconds (queued for 1 second)
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  Build
passed build-debian-clang #3251
librem5

00:02:48

passed build-debian-gcc #3250
librem5

00:02:16

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passed build-debian-package #3252
librem5

00:02:12