eval-release.sh: increase nix-instantiate heap size to 2GB

Otherwise, nix-instantiate fails with
Too many heap sections: Increase MAXHINCR or MAX_HEAP_SECTS

maintainers/scripts/eval-release.sh

@@ -4,4 +4,8 @@ if [[ -z "$VERBOSE" ]]; then
   echo "You may set VERBOSE=1 to see debug output or to any other non-empty string to make this script completely silent"
 fi
 unset HOME NIXPKGS_CONFIG # Force empty config
+
+# With the default heap size (380MB), nix-instantiate fails:
+# Too many heap sections: Increase MAXHINCR or MAX_HEAP_SECTS
+export GC_INITIAL_HEAP_SIZE=${GC_INITIAL_HEAP_SIZE:-2000000000} # 2GB
 nix-instantiate --strict --eval-only --xml --show-trace "$(dirname "$0")"/eval-release.nix 2>&1 > /dev/null