devtools/credit: ! not ^ to invert the match set in sh.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

devtools/credit

@@ -25,8 +25,8 @@ NAMER=""
 BACKUP_NAMER=""
 TOTAL=0
 while read LINE; do
-    COUNT=${LINE%% [^ 0123456789]*}
-    TOTAL=$(($TOTAL + $COUNT))
+    COUNT=${LINE%% [! 0123456789]*}
+    TOTAL=$((TOTAL + COUNT))
     LINE=${LINE#*[1234567890] }
     NAME=${LINE%%|*}
     EMAIL=${LINE#*|}