add showing a string to REPL precompile workload (#58157)

Author: KristofferC

stdlib/REPL/src/precompile.jl

@@ -58,6 +58,7 @@ function repl_workload()
     printstyled("a", "b")
     display([1])
     display([1 2; 3 4])
+    display("a string")
     foo(x) = 1
     @time @eval foo(1)
     ; pwd