Port to <str> return values from RPM. BZ 1851499
    
    These regexes are matched against the data returned from the RPM header
    functions further down the code, however the format of the data has
    recently changed from <bytes> objects to decoded <str> objects, so we
    should no longer declare the regexes as bytes.
    
    Basically an inverse of the following two commits:
    32581a87e3b00396c7dc2c8b6d1779ffe873abfb
    d93953b644dfe26f923d8d95d1a0ab6a433ae0f1
    
    Details on the RPM change:
    https://github.com/rpm-software-management/rpm/commit/84920f898315d09a57a3f1067433eaeb7de5e830