krb5 config parsing issues when auth_to_local_names is specified

[antbbn]

I noticed that when auth_to_local_names is specified in the krb5 config parsing results in a panic.
For example adding this to a realm in the test krb5Conf (v8/config/krb5conf_test.go):

        auth_to_local_names = {
                name = othername
        }

Results in:

[antbbn@fedora config]$ go test
--- FAIL: TestResolveRealm (0.00s)
panic: runtime error: index out of range [1] with length 1 [recovered]
	panic: runtime error: index out of range [1] with length 1

goroutine 34 [running]:
testing.tRunner.func1.2({0x5f6200, 0xc000252030})
	/usr/lib/golang/src/testing/testing.go:1631 +0x24a
testing.tRunner.func1()
	/usr/lib/golang/src/testing/testing.go:1634 +0x377
panic({0x5f6200?, 0xc000252030?})
	/usr/lib/golang/src/runtime/panic.go:770 +0x132
github.com/jcmturner/gokrb5/v8/config.(*Realm).parseLines(0xc0003177f8, {0xc0000ac631?, 0x66f2c8?}, {0xc0002701d8?, 0x0?, 0xc00009c370?})
	/home/antbbn/gokrb5/v8/config/krb5conf.go:379 +0xdfe
github.com/jcmturner/gokrb5/v8/config.parseRealms({0xc000270118, 0x1a, 0x36})
	/home/antbbn/gokrb5/v8/config/krb5conf.go:447 +0x39e
github.com/jcmturner/gokrb5/v8/config.NewFromScanner(0xc000317d90)
	/home/antbbn/gokrb5/v8/config/krb5conf.go:591 +0x79e
github.com/jcmturner/gokrb5/v8/config.NewFromReader({0x6709e0?, 0xc0004d76c0?})
	/home/antbbn/gokrb5/v8/config/krb5conf.go:537 +0x68
github.com/jcmturner/gokrb5/v8/config.NewFromString({0x61c065, 0x6e4})
	/home/antbbn/gokrb5/v8/config/krb5conf.go:531 +0x6f
github.com/jcmturner/gokrb5/v8/config.TestResolveRealm(0xc000208000)
	/home/antbbn/gokrb5/v8/config/krb5conf_test.go:644 +0x3b
testing.tRunner(0xc000208000, 0x637cb8)
	/usr/lib/golang/src/testing/testing.go:1689 +0xfb
created by testing.(*T).Run in goroutine 1
	/usr/lib/golang/src/testing/testing.go:1742 +0x390
exit status 2
FAIL	github.com/jcmturner/gokrb5/v8/config	0.020s

The issue seems to stem from the fact that in parseLines when a line with a single } is encountered and the section was not explictly ignored (eg. ignore = true) the line is split and the second element is accessed.

The following diff fixes the issue for my test case and, looking at the docs, I don't think there are other non v4 subsections in [realms] (v4 ones are correctly ignored). Not sure if the panic can be triggered in other sections of krb5.conf.
If you would like me to make a PR i'll be happy to.

diff --git a/v8/config/krb5conf.go b/v8/config/krb5conf.go
index f448c8a..7c7f36e 100644
--- a/v8/config/krb5conf.go
+++ b/v8/config/krb5conf.go
@@ -354,6 +354,9 @@ func (r *Realm) parseLines(name string, lines []string) (err error) {
                        ignore = true
                        err = UnsupportedDirective{"v4 configurations are not supported"}
                }
+               if strings.Contains(line, "auth_to_local_names") {
+                       ignore = true
+               }
                if strings.Contains(line, "{") {
                        c++
                        if ignore {

Some details:
gokrb5 version: master and 8.4.4
go version: go version go1.22.11 linux/amd64 (was unable to install an earlier one)
environment: not relevant for this issue