switch golangci-lint to v2 for go v1.25 support and migrate lint config

go v1.25 is now required by the dependencies we pull in (coder/v2).

- pin golangci-lint to v2.4.0 in CI
- update .golangci.yml to v2 schema (default none, formatter config, settings move)
- bump golangci-lint-action to v8 so v2.x installs correctly

Author: geokat

.github/workflows/test.yml

@@ -36,9 +36,11 @@ jobs:
       - run: go build -v .
 
       - name: Run linters
-        uses: golangci/golangci-lint-action@2226d7cb06a077cd73e56eedd38eecad18e5d837 # v6.5.0
+        uses: golangci/golangci-lint-action@v8
         with:
-          version: latest
+          # Pin to v2.4.0+ because it is the first golangci-lint release that
+          # supports Go 1.25.
+          version: v2.4.0
 
   generate:
     runs-on: ubuntu-latest
@@ -112,7 +114,7 @@ jobs:
 
       - uses: actions/setup-go@7a3fe6cf4cb3a834922a1244abfce67bcef6a0c5 # v6.2.0
         with:
-          go-version: "1.25.6"
+          go-version-file: "go.mod"
         id: go
 
       - uses: hashicorp/setup-terraform@b9cd54a3c349d3f38e8881555d616ced269862dd # v3.1.2

.golangci.yml

@@ -1,18 +1,18 @@
+version: "2"
+
 # Visit https://golangci-lint.run/ for usage documentation and information on
 # other useful linters
 issues:
   max-issues-per-linter: 0
   max-same-issues: 0
 
 linters:
-  disable-all: true
+  default: none
   enable:
     - durationcheck
     - errcheck
     - forcetypeassert
     - godot
-    - gofmt
-    - gosimple
     - govet
     - ineffassign
     - makezero
@@ -25,9 +25,12 @@ linters:
     - unparam
     - unused
     - usetesting
+  settings:
+    paralleltest:
+      # Terraform acceptance subtests all share a Coder instance, and cannot run
+      # in parallel.
+      ignore-missing-subtests: true
 
-linters-settings:
-  paralleltest:
-    # Terraform acceptance subtests all share a Coder instance, and cannot run
-    # in parallel.
-    ignore-missing-subtests: true
+formatters:
+  enable:
+    - gofmt