Stop pinning Go to patch versions, use stable in CI

Drop the patch version from the go directive in go.mod (1.26.2 → 1.26)
so we only declare the minimum language version needed. Switch all CI
workflows to go-version: 'stable' so they always use the latest stable
Go release. Remove the Renovate custom manager that was bumping the Go
patch version — no longer needed.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: rdimitrov

.github/workflows/license-headers.yml

@@ -19,7 +19,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6.4.0
         with:
-          go-version-file: 'go.mod'
+          go-version: 'stable'
           cache: false
 
       - name: Install addlicense

.github/workflows/lint.yml

@@ -19,7 +19,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6.4.0
         with:
-          go-version-file: 'go.mod'
+          go-version: 'stable'
           cache: true
           cache-dependency-path: go.sum
 

.github/workflows/security.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Run govulncheck
         uses: golang/govulncheck-action@b625fbe08f3bccbe446d94fbf87fcc875a4f50ee # v1.0.4
         with:
-          go-version-file: go.mod
+          go-version-input: 'stable'
           go-package: ./...
           repo-checkout: false
 

.github/workflows/test.yml

@@ -19,7 +19,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6.4.0
         with:
-          go-version-file: 'go.mod'
+          go-version: 'stable'
           cache: true
           cache-dependency-path: go.sum
 

go.mod

@@ -1,6 +1,6 @@
 module github.com/stacklok/toolhive-core
 
-go 1.26.2
+go 1.26
 
 require (
 	github.com/adrg/xdg v0.5.3

renovate.json

@@ -6,15 +6,5 @@
     ":semanticCommitsDisabled"
   ],
   "labels": ["dependencies"],
-  "postUpdateOptions": ["gomodTidy"],
-  "customManagers": [
-    {
-      "customType": "regex",
-      "fileMatch": ["(^|/)go\\.mod$"],
-      "matchStrings": ["go (?<currentValue>\\d+\\.\\d+(\\.\\d+)?)"],
-      "depNameTemplate": "golang",
-      "datasourceTemplate": "golang-version",
-      "versioningTemplate": "loose"
-    }
-  ]
+  "postUpdateOptions": ["gomodTidy"]
 }