[tgross]

Update the Go toolchain to pick up fixes for a small pile of CVEs in the stdlib.

Includes a test fix for our helper/ipaddr package to match current stdlib parsing. From upstream's description of CVE-2025-47912:

The Parse function permitted values other than IPv6 addresses to be included
in square brackets within the host component of a URL. RFC 3986 permits IPv6
addresses to be included within the host component, enclosed within square
brackets. For example: "http://[::1]/". IPv4 addresses and hostnames must not
appear within square brackets. Parse did not enforce this requirement.

Ref: https://go.dev/doc/devel/release#go1.25.2

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Changes to Security Controls

Are there any changes to security controls (access controls, encryption, logging) in this pull request? If so, explain.

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