fix: use pull_request_target instead of pull_request

[sysulq]

Describe what this PR does / why we need it

Does this pull request fix one issue?

Describe how you did it

Describe how to verify it

Special notes for reviews

[codecov-commenter]

Codecov Report

Merging #640 (5401b9a) into master (08a6bed) will decrease coverage by 17.40%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master     #640       +/-   ##
===========================================
- Coverage   52.69%   35.29%   -17.41%     
===========================================
  Files         189      151       -38     
  Lines       10027     7390     -2637     
===========================================
- Hits         5284     2608     -2676     
- Misses       4361     4578      +217     
+ Partials      382      204      -178     

Impacted Files	Coverage Δ
pkg/core/sentinel/sentinel_circuitbreaker.go	0.00% <0.00%> (-100.00%)	⬇️
pkg/util/xgo/serial.go	0.00% <0.00%> (-96.78%)	⬇️
pkg/util/xcast/cast.go	0.00% <0.00%> (-91.67%)	⬇️
pkg/util/xgo/parallel.go	0.00% <0.00%> (-86.80%)	⬇️
pkg/util/xretry/retry.go	15.38% <0.00%> (-84.62%)	⬇️
pkg/util/xstring/conv.go	0.00% <0.00%> (-84.22%)	⬇️
pkg/server/governor/server.go	0.00% <0.00%> (-75.68%)	⬇️
pkg/util/xfile/filestat_posix.go	0.00% <0.00%> (-75.00%)	⬇️
pkg/core/sentinel/config.go	2.85% <0.00%> (-67.15%)	⬇️
pkg/client/redis/interceptor.go	26.50% <0.00%> (-64.32%)	⬇️
... and 70 more

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.