go.mod: change agent remote-config package enforcing our working fork

[Julio-Guerra]

What does this PR do?

This patch release fixes #1607 with Go modules version selection when dd-trace-go is updated using go get -u all, where an unstable indirect dependency was unexpectedly upgrading to an incompatible version and therefore leading to a compilation error.

Motivation

Avoid go get -u all issue.

Describe how to test/QA your changes

Reviewer's Checklist

• If known, an appropriate milestone has been selected; otherwise the Triage milestone is set.
• Changed code has unit tests for its functionality.
• If this interacts with the agent in a new way, a system test has been added.

[pr-commenter]

Benchmarks

Comparing candidate commit 5a0236b in PR branch julio.guerra/backport-go-tuf-fix with baseline commit 5639eb2 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 6 cases.