v2.16.1

• Fix substreams/firehose endpoints detection of supported compression: do not fail on 'algo;q=x.y' syntax
• Fix relayer failing to get back to live if reader blocks are unlinkable after a long period, and merger has removed one-blocks: it will now shutdown in that case, so it can be restarted.
• Fix substreams tier2 jobs behind load balancer: will now retry forever on 'Unavailable: no healthy upstream' errors
• Add substreams-tier2-authenticator flag to specify the authenticator to use for tier2 requests. Can be 'trust://' (default, same as previous behavior) or 'secret://'
• Add substreams-tier1-subrequests-secret-key flag to specify the secret key to use for tier1 subrequests authentication when using 'secret://' authenticator on tier2
• Add reader-node-grpc-secret-key flag to specify the secret key to use for reader node gRPC authentication
• Add ?secret=... parsing to relayer-sources
• Add Prometheus metrics for reader test mode: track blocks compared, success/failure counts, and success/failure percentages for easy monitoring at interval stats.