Upgrade Bor to v2.8.3 With Critical Fixes

Bor v2.8.3 released. Maintenance upgrade with bug fixes. Stop service, install via curl script with version tag, network (amoy/mainnet), and node type (sentry/validator/archive). Verify `/usr/bin/bor version` prints v2.8.3. Restart. Docker images available for Bor and Erigon.