dev-go/net: update to v0.55.0

Update dev-go/net in policy manager to v0.55.0.
This fixes CVE-2026-25680.

BUG=b/536227571
TEST=emerge-lakitu dev-go/net sys-apps/policymanager, presubmit
RELEASE_NOTE=Update dev-go/net to v0.55.0 to fix CVE-2026-25680.

cos-patch: security-high
Change-Id: Ia36891e7aa92572d374d16d1ef1f47eaf9f9fd37
Reviewed-on: https://cos-review.googlesource.com/c/third_party/overlays/chromiumos-overlay/+/194447
Main-Branch-Verified: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Miri Amarilio <mirilio@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>