Update distinfo, due to checksum mismatches on download.

Side-by-side comparison of the old and new distfiles shows that
upstream have apparently rerolled the distfile, with changes to the
content. However these changes are innocuous and consist of updating
some autoconf related files changing an embedded version string from
7.5devel to 7.5.0

Affected files:

% diff -qr pg_citus.{orig,newest}
Files pg_citus.orig/citus-7.5.0/configure and pg_citus.newest/citus-7.5.0/configure differ
Files pg_citus.orig/citus-7.5.0/configure.in and pg_citus.newest/citus-7.5.0/configure.in differ
Files pg_citus.orig/citus-7.5.0/src/test/regress/expected/multi_extension.out and pg_citus.newest/citus-7.5.0/src/test/regress/expected/multi_extension.out differ

Reported by: olgeni, pkg-fallout