attestation: improve error message when gh is too old

Library/Homebrew/attestation.rb

@@ -14,6 +14,9 @@ module Attestation
     # @api private
     HOMEBREW_CORE_REPO = "Homebrew/homebrew-core"
 
+    # @api private
+    GH_ATTESTATION_MIN_VERSION = Version.new("2.49.0").freeze
+
     # @api private
     BACKFILL_REPO = "trailofbits/homebrew-brew-verify"
 
@@ -104,6 +107,11 @@ def self.check_attestation(bottle, signing_repo, signing_workflow = nil, subject
         # Even if we have credentials, they may be invalid or malformed.
         raise GhAuthNeeded, "invalid credentials" if e.status.exitstatus == 4
 
+        if Formula["gh"].any_installed_version.version < GH_ATTESTATION_MIN_VERSION
+          raise e,
+                "`gh` is too old, you must run `brew upgrade gh` to continue."
+        end
+
         raise InvalidAttestationError, "attestation verification failed: #{e}"
       end