ci: Update setup-go to use Go version from go.mod

This uses the ecosystem standard of defining the minimum Go version to build
the package, as well as the Go toolchain the release is built with.

Author: jalseth

.github/workflows/pr.yaml

@@ -17,8 +17,7 @@ jobs:
       - name: setup go
         uses: actions/setup-go@44694675825211faa026b3c33043df3e48a5fa00 # ratchet:actions/setup-go@v6
         with:
-          go-version: "1.25.x"
-          cache: false
+          go-version-file: 'go.mod'
 
       - name: validate conventional commit prefix
         working-directory: scripts
@@ -71,8 +70,7 @@ jobs:
       - name: setup go
         uses: actions/setup-go@44694675825211faa026b3c33043df3e48a5fa00 # ratchet:actions/setup-go@v6
         with:
-          go-version: "1.25.x"
-          cache: false
+          go-version-file: 'go.mod'
 
       - name: build
         run: make build

.github/workflows/release.yaml

@@ -105,7 +105,7 @@ jobs:
       - name: setup go
         uses: actions/setup-go@44694675825211faa026b3c33043df3e48a5fa00 # ratchet:actions/setup-go@v6
         with:
-          go-version: "1.25.x"
+          go-version-file: 'go.mod'
 
       - name: release
         uses: goreleaser/goreleaser-action@e435ccd777264be153ace6237001ef4d979d3a7a # ratchet:goreleaser/goreleaser-action@v6

go.mod

@@ -2,6 +2,8 @@ module github.com/open-policy-agent/conftest
 
 go 1.25.3
 
+toolchain go1.25.6
+
 require (
 	cuelang.org/go v0.15.3
 	github.com/BurntSushi/toml v1.6.0