chore: bump inspektor-gadget fork to latest main (#921)

The fork (matthyx/inspektor-gadget) was reset onto upstream v0.48.1
with its fork-specific commits reapplied and cleaned up; this picks
up the corrected datasource pooling implementation (matching
upstream PR inspektor-gadget/inspektor-gadget#5295) and the
uprobetracer/TLS reattach fixes.

Docs-exempt: pure dependency version bump (go.mod/go.sum only), no behavioral change to this repo's own code