add test for @field with other decorators

[BurnzZ]

Used as an example in zytedata/zyte-common-items#15 (comment)

[codecov]

Codecov Report

Merging #82 (34eb0ec) into master (e4b9603) will not change coverage.
The diff coverage is n/a.

❗ Current head 34eb0ec differs from pull request most recent head 7a290ed. Consider uploading reports for the commit 7a290ed to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #82   +/-   ##
=======================================
  Coverage   99.81%   99.81%           
=======================================
  Files          17       17           
  Lines         536      536           
=======================================
  Hits          535      535           
  Misses          1        1           

[kmike]

Thanks @BurnzZ!