fix(go): add pkg/errors transitive dep required by evanphx/json-patch

github.com/evanphx/json-patch imports github.com/pkg/errors; both go.sum
hashes and the go.mod indirect entry were missing, causing the CI "Go build
& test" check to fail with a missing go.sum entry error.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 2 people

go.mod

@@ -46,6 +46,7 @@ require (
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/mxk/go-flowrate v0.0.0-20140419014527-cca7078d478f // indirect
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
 	golang.org/x/crypto v0.21.0 // indirect
 	golang.org/x/net v0.23.0 // indirect

go.sum

@@ -79,6 +79,8 @@ github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
 github.com/mxk/go-flowrate v0.0.0-20140419014527-cca7078d478f h1:y5//uYreIhSUg3J1GEMiLbxo1LJaP8RfCpH6pymGZus=
 github.com/mxk/go-flowrate v0.0.0-20140419014527-cca7078d478f/go.mod h1:ZdcZmHo+o7JKHSa8/e818NopupXU1YMK5fe1lsApnBw=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/onsi/ginkgo/v2 v2.15.0 h1:79HwNRBAZHOEwrczrgSOPy+eFTTlIGELKy5as+ClttY=
 github.com/onsi/ginkgo/v2 v2.15.0/go.mod h1:HlxMHtYF57y6Dpf+mc5529KKmSq9h2FpCF+/ZkwUxKM=
 github.com/onsi/gomega v1.31.0 h1:54UJxxj6cPInHS3a35wm6BK/F9nHYueZ1NVujHDrnXE=