d/rules: Fix FTBFS; DEB_VERSION_UPSTREAM is blank without pkg-info.mk

Dave Jonesrequested to merge
waveform/device-tree-compiler:fix-ftbfs into debian/master

While looking into an FTBFS on Ubuntu, we noticed DEB_VERSION_UPSTREAM (which is used to force setuptools-scm's version via SETUPTOOLS_SCM_PRETEND_VERSION in d/rules) is blank because the include for pkg-info.mk is missing.

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