Update module lib/pq to v1.6.0 (#572)

Update module lib/pq to v1.6.0

Reviewed-on: https://kolaente.dev/vikunja/api/pulls/572

vendor/github.com/lib/pq/krb.go

@@ -0,0 +1,40 @@
+package pq
+
+import (
+	"net"
+	"strings"
+)
+
+/*
+ *  Basic GSSAPI interface to abstract Windows (SSPI) from Unix
+ *  APIs within the driver
+ */
+
+type Gss interface {
+	GetInitToken(host string, service string) ([]byte, error)
+	GetInitTokenFromSpn(spn string) ([]byte, error)
+	Continue(inToken []byte) (done bool, outToken []byte, err error)
+}
+
+/*
+ *  Find the A record associated with a hostname
+ *  In general, hostnames supplied to the driver should be
+ *  canonicalized because the KDC usually only has one
+ *  principal and not one per potential alias of a host.
+ */
+func canonicalizeHostname(host string) (string, error) {
+	canon := host
+
+	name, err := net.LookupCNAME(host)
+	if err != nil {
+		return "", err
+	}
+
+	name = strings.TrimSuffix(name, ".")
+
+	if name != "" {
+		canon = name
+	}
+
+	return canon, nil
+}