Update go to 1.23 and plumbing vendoring (#1284)

The vendored version of tektoncd/plumbing is from 2023.
Updating plumbing brings in an update of golang as well to 1.23.

Signed-off-by: Andrea Frittoli <andrea.frittoli@uk.ibm.com>

go.mod

@@ -2,7 +2,7 @@ module github.com/tektoncd/chains
 
 go 1.23.2
 
-toolchain go1.23.3
+toolchain go1.23.4
 
 require (
 	cloud.google.com/go/compute/metadata v0.6.0
@@ -31,7 +31,7 @@ require (
 	github.com/spiffe/go-spiffe/v2 v2.4.0
 	github.com/stretchr/testify v1.10.0
 	github.com/tektoncd/pipeline v0.66.0
-	github.com/tektoncd/plumbing v0.0.0-20230907180608-5625252a2de1
+	github.com/tektoncd/plumbing v0.0.0-20250115133002-f515628dffea
 	go.opencensus.io v0.24.0
 	go.uber.org/zap v1.27.0
 	gocloud.dev v0.40.0

go.sum

@@ -1310,8 +1310,8 @@ github.com/tdakkota/asciicheck v0.2.0 h1:o8jvnUANo0qXtnslk2d3nMKTFNlOnJjRrNcj0j9
 github.com/tdakkota/asciicheck v0.2.0/go.mod h1:Qb7Y9EgjCLJGup51gDHFzbI08/gbGhL/UVhYIPWG2rg=
 github.com/tektoncd/pipeline v0.66.0 h1:WLL98YEgWzblSAD2mPbpZN97tkOC50wiftaW+8+6zTY=
 github.com/tektoncd/pipeline v0.66.0/go.mod h1:V3cyfxxc7b3GLT2a13GX2mWA86qmxWhh4mOp4gfFQwQ=
-github.com/tektoncd/plumbing v0.0.0-20230907180608-5625252a2de1 h1:9paprRIBXQgcvdhGq3wKiSspXP0JIFSY52ru3sIMjKM=
-github.com/tektoncd/plumbing v0.0.0-20230907180608-5625252a2de1/go.mod h1:7eWs1XNkmReggow7ggRbRyRuHi7646B8b2XipCZ3VOw=
+github.com/tektoncd/plumbing v0.0.0-20250115133002-f515628dffea h1:z7uBS+485zM5dFs/ixc708MgIO8eCWPCRCreUQC/pzI=
+github.com/tektoncd/plumbing v0.0.0-20250115133002-f515628dffea/go.mod h1:Ks1fp1nPnhJxxT810eOkq2skeIiDuYjq3cIgpS5Gxk4=
 github.com/tenntenn/modver v1.0.1 h1:2klLppGhDgzJrScMpkj9Ujy3rXPUspSjAcev9tSEBgA=
 github.com/tenntenn/modver v1.0.1/go.mod h1:bePIyQPb7UeioSRkw3Q0XeMhYZSMx9B8ePqg6SAMGH0=
 github.com/tenntenn/text/transform v0.0.0-20200319021203-7eef512accb3 h1:f+jULpRQGxTSkNYKJ51yaw6ChIqO+Je8UqsTKN/cDag=