Remove colours from test times

The implementation is slightly awkward, and will be much more so when we'll want to count characters for nicer terminal layout. It's maybe not the best UX anyway. We'll think about alternatives.

haskell/Pre.hs

@@ -315,9 +315,7 @@ displayTestResultsConsole testResult =
         T.show res
             <> T.singleton '.'
             <> T.take (if isNothing unit then 3 else 2) (T.show frac <> "000")
-            <> case unit of
+            <> foldMap T.singleton unit
-                Nothing -> setColour Dull Red
-                Just (u, h) -> setColour Dull h <> T.singleton u
             <> T.singleton 's'
       where
         (frac, res, unit) = case duration of
@@ -331,10 +329,10 @@ displayTestResultsConsole testResult =
                         ( carried
                         , r
                         , Just case iterations of
-                            3 -> ('m', Yellow)
+                            3 -> 'm'
-                            2 -> ('μ', Green)
+                            2 -> 'μ'
-                            1 -> ('n', Green)
+                            1 -> 'n'
-                            _ -> ('p', Green)
+                            _ -> 'p'
                         )
                     (d, r) -> go (succ iterations) r d
     sgr = T.pack . setSGRCode