qpdf: Update to version 11.6.1

qpdf: Update to version 11.6.1

- Update from version 11.5.0 to 11.6.1
- Update of rootfile
- Changelog
    11.6.1: release
        * Fix a logic error introduced in 11.6.0 in the fix to
          copyForeignObject. The bug could result in some pages not being
          copied.
    11.6.0: release
        * ascii85 parser: ignore spaces everywhere including between ~
          and >. Fixes #973.
        * Bug fix: with --pages, if one of the external files had warnings
          but the main file did not, the warning was previously not taken
          into consideration when determining the exit status.
        * Put quotation marks around the command in completion output to
          better handle spaces in paths. It is not a perfect fix (ideally,
          full shell-compatible quoting should be used), but it handles more
          cases than the old code and should handle all reasonable cases of
          qpdf being in a directory with a space in its name, which is
          common in Windows. Fixes #1021.
        * Move check for random number device to runtime instead of
          compile time. Since, by default, the crypto provider provides
          random numbers, runtime determination of a random number device is
          usually not needed. Fixes #1022.
        * Maintain links to foreign pages when copying foreign objects.
          This allows hyperlinks in imported files to work. Fixes #1003.
        * Bug fix: Return a null object if an attempt is made to to copy a
          foreign /Pages object with copyForeignObject. This corrects a
          possible crash. Fixes #1010.
        * Bug fix: Return a null object if an attempt is made to to copy a
          foreign /Pages object with copyForeignObject. Fixes #1003.
        * Add /MediaBox to a page if absent. Thanks M. Holger.
        * Use std::vector internally for Pl_Buffer to
          avoid incompatibility with C++20. Thanks to Zoe Clifford. Fixes #1024.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>