Renovate: Update dependency go to v1.25.3

Author: renovate[bot]

go.mod

@@ -2,7 +2,7 @@ module github.com/sapcc/argora
 
 go 1.25
 
-toolchain go1.25.1
+toolchain go1.25.3
 
 require (
 	github.com/dspinhirne/netaddr-go/v2 v2.0.0