`IPv6Network.next_network()` raises the wrong error when addresses run out

Bug description:

_BaseNetwork.next_network() guards address-space exhaustion with except OverflowError, which only the IPv4 path raises, so on IPv6 the internal ValueError from _string_from_ip_int() escapes instead.

from ipaddress import IPv4Network, IPv6Network

for net in (IPv4Network('255.255.255.0/24'),
            IPv6Network('ffff:ffff:ffff:ffff:ffff:ffff:ffff:0/112')):
    try:
        net.next_network()
    except ValueError as e:
        print(f"{net}: {e}")

Output:

255.255.255.0/24: out of address space, cannot make another /24 network
ffff:ffff:ffff:ffff:ffff:ffff:ffff:0/112: IPv6 address is too large

Expected: out of address space, cannot make another /112 network, the message Doc/library/ipaddress.rst gives for next_network().

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-156681
• gh-157280

檢查 _BaseNetwork.next_network() 以及 Doc/library/ipaddress.rst 中對 next_network() 的措辭，然後重現 issue 中的 IPv4 和 IPv6 範例。完成標準是：對於 /112 網路，IPv6 位址空間耗盡時回報文件中所述的「out of address space」訊息，而不是「IPv6 address is too large」。