patch 8.2.1618: Vim9: cannot pass "true" to setloclist()

Problem:    Vim9: cannot pass "true" to setloclist().
Solution:   Use dict_get_bool(). (closes #6882)
diff --git a/src/quickfix.c b/src/quickfix.c
index 09d5d8f..c8858b4 100644
--- a/src/quickfix.c
+++ b/src/quickfix.c
@@ -7072,7 +7072,7 @@
 
     // If the 'valid' field is present it overrules the detected value.
     if ((dict_find(d, (char_u *)"valid", -1)) != NULL)
-	valid = (int)dict_get_number(d, (char_u *)"valid");
+	valid = (int)dict_get_bool(d, (char_u *)"valid", FALSE);
 
     status =  qf_add_entry(qfl,
 			NULL,		// dir