Fix: Don't run benchmark comment for forks

[dqii]

See: https://github.com/peter-evans/create-pull-request/blob/main/docs/concepts-guidelines.md#restrictions-on-repository-forks

[github-actions[bot]]

Benchmarks

metric	old	new	pct change
recall (after create)	-	0.740	-
recall (after insert)	-	0.784	-
select tps	-	3810.250	-
select latency (ms)	-	1.551	-
create latency (ms)	-	1444.288	-
insert latency (ms)	-	1.762	-
insert tps	-	567.020	-
disk usage (bytes)	-	6348800.000	-

[codecov[bot]]

Codecov Report

Merging #132 (dcb7253) into main (accceec) will not change coverage. The diff coverage is n/a.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #132 +/- ## ======================================= Coverage 83.79% 83.79% ======================================= Files 13 13 Lines 1086 1086 Branches 244 244 ======================================= Hits 910 910 Misses 78 78 Partials 98 98 ```