feat: Support customized delayed tasks key in redigo implementation

[tori3ama]

goredis implementation supported this long time ago, which should also be supported in redigo implementation

[codecov]

Codecov Report

Merging #595 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #595   +/-   ##
=======================================
  Coverage   39.38%   39.38%           
=======================================
  Files          32       32           
  Lines        3344     3344           
=======================================
  Hits         1317     1317           
  Misses       1885     1885           
  Partials      142      142           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 7bf3910...c9d54fe. Read the comment docs.