caddyhttp: fix randString sameCase dictionary to match its docs

The doc comment says randString excludes confusing characters like
I, l, 1, 0, O. When sameCase is true, uppercase letters are excluded,
and l and o should also be excluded. But the dictionary used when
sameCase was true still contained '0'. Drop it, and update the test
to match the actual documented exclusions.

Signed-off-by: Mohammed Al Sahaf <msaa1990@gmail.com>

modules/caddyhttp/errors.go

@@ -96,7 +96,7 @@ func randString(n int, sameCase bool) string {
 	}
 	dict := []byte("abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRTUVWXY23456789")
 	if sameCase {
-		dict = []byte("abcdefghijkmnpqrstuvwxyz0123456789")
+		dict = []byte("abcdefghijkmnpqrstuvwxyz123456789")
 	}
 	b := make([]byte, n)
 	for i := range b {

modules/caddyhttp/errors_utils_test.go

@@ -164,7 +164,7 @@ func TestRandString_NoConfusingChars(t *testing.T) {
 		{
 			name:     "same case excludes l,0",
 			sameCase: true,
-			excluded: []rune{'l', 'o'},
+			excluded: []rune{'l', '0'},
 		},
 	}