Don't assume Bash flags for BASH_REMATCH (#30)

This makes the test work with all versions of Bash 5.x

Author: jansorg

test/data/bash-rematch.cmd

@@ -9,7 +9,7 @@ c
 s
 c
 s
-eval typeset -p BASH_REMATCH
+eval typeset | grep -E '^BASH_REMATCH='
 c
 s
 c

test/data/bash-rematch.right

@@ -30,8 +30,8 @@ Breakpoint 1 hit (2 times).
 (bash-rematch.sh:8):
 8:	    echo "${!i} matches"
  0: $BASH_REMATCH = 456
-+eval typeset -p BASH_REMATCH
-declare -a BASH_REMATCH=([0]="456")
++eval typeset | grep -E '^BASH_REMATCH='
+BASH_REMATCH=([0]="456")
 $? is 0
 +c
 456 matches