community/networkmanager: upgrade to 1.38.2

From the changelog:

• Fix race condition with pppd that caused failures when activating PPPoE connections.
• Unbreak DHCPv6 over PPP.
• Don't ignore IPv6 DNS servers received from PPP.
• Fix crash while checking WEP capability of Wi-Fi interfaces.
• Ensure DHCP is restarted every time the link goes up.
• Fix struct alignment issues seen on some architectures.
• Various other bugfixes and improvements.

In particular I need this for the ipv6 fixes over ppp, so I'll [open a] backport [MR for] this to 3.16 as soon as this is merged.

Thanks!