ci: improve the output

The markup ##[...] makes GHA groups outputs together, making it easy to
compare results across runs.

tests/circomlib-test.rkt

@@ -12,6 +12,7 @@
 
   (define-check (check-result filename expected)
     (printf "=== checking ~a ===\n" filename)
+    (printf "##[group]~a\n" filename)
     (define-values (in out) (make-pipe))
     (define orig-out (current-output-port))
     (define string-port (open-output-string))
@@ -25,9 +26,12 @@
                                                      (format "~a.r1cs" filename))))]
                    [current-output-port out])
       (define thd (thread (λ () (copy-port in orig-out string-port))))
-      (time (dynamic-require picus #f))
+      (match-define-values (_ cpu real gc)
+        (time-apply (λ () (dynamic-require picus #f)) '()))
       (close-output-port out)
-      (thread-wait thd))
+      (thread-wait thd)
+      (printf "##[endgroup]\n")
+      (printf "cpu: ~a; real: ~a; gc: ~a\n" cpu real gc))
     (check-regexp-match
      (match expected
        ['safe #px"(?m:^# weak uniqueness: safe\\.$)"]