chore(deps): bump github.com/a2aproject/a2a-go from 0.3.9 to 0.3.12

Bumps [github.com/a2aproject/a2a-go](https://github.com/a2aproject/a2a-go) from 0.3.9 to 0.3.12.
- [Release notes](https://github.com/a2aproject/a2a-go/releases)
- [Changelog](https://github.com/a2aproject/a2a-go/blob/v0.3.12/CHANGELOG.md)
- [Commits](a2aproject/a2a-go@v0.3.9...v0.3.12)

---
updated-dependencies:
- dependency-name: github.com/a2aproject/a2a-go
  dependency-version: 0.3.12
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

go.mod

@@ -3,7 +3,7 @@ module github.com/plexusone/agentkit
 go 1.25.5
 
 require (
-	github.com/a2aproject/a2a-go v0.3.9
+	github.com/a2aproject/a2a-go v0.3.12
 	github.com/cloudwego/eino v0.8.4
 	github.com/go-playground/validator/v10 v10.30.1
 	github.com/grokify/mogo v0.74.0

go.sum

@@ -4,8 +4,8 @@ cloud.google.com/go/auth v0.18.2 h1:+Nbt5Ev0xEqxlNjd6c+yYUeosQ5TtEUaNcN/3FozlaM=
 cloud.google.com/go/auth v0.18.2/go.mod h1:xD+oY7gcahcu7G2SG2DsBerfFxgPAJz17zz2joOFF3M=
 cloud.google.com/go/compute/metadata v0.9.0 h1:pDUj4QMoPejqq20dK0Pg2N4yG9zIkYGdBtwLoEkH9Zs=
 cloud.google.com/go/compute/metadata v0.9.0/go.mod h1:E0bWwX5wTnLPedCKqk3pJmVgCBSM6qQI1yTBdEb3C10=
-github.com/a2aproject/a2a-go v0.3.9 h1:Vo7WuGDKaKhOgDTkhhcbYlwhM7Fkh7jPmh/eKmsPo9w=
-github.com/a2aproject/a2a-go v0.3.9/go.mod h1:I7Cm+a1oL+UT6zMoP+roaRE5vdfUa1iQGVN8aSOuZ0I=
+github.com/a2aproject/a2a-go v0.3.12 h1:l5Yd0UgZrZyEuiMRlj3ybiqxmqXvVhJ8bTyWB7ZlJ2o=
+github.com/a2aproject/a2a-go v0.3.12/go.mod h1:I7Cm+a1oL+UT6zMoP+roaRE5vdfUa1iQGVN8aSOuZ0I=
 github.com/airbrake/gobrake v3.6.1+incompatible/go.mod h1:wM4gu3Cn0W0K7GUuVWnlXZU11AGBXMILnrdOU8Kn00o=
 github.com/bahlo/generic-list-go v0.2.0 h1:5sz/EEAK+ls5wF+NeqDpk5+iNdMDXrh3z3nPnH1Wvgk=
 github.com/bahlo/generic-list-go v0.2.0/go.mod h1:2KvAjgMlE5NNynlg/5iLrrCCZ2+5xWbdbCW3pNTGyYg=