chore: Fix Renovate config (#3635)

# Summary

Fixes renovate config to use the
[`config:best-practices`](https://docs.renovatebot.com/presets-config/#configbest-practices)
preset rather than the `config:base` preset since `config:base` seems to
have gone away at some point.

Also fixes the `schedule` config by using the
[`schedule:monthly`](https://docs.renovatebot.com/presets-schedule/#schedulemonthly)
preset. The previous `schedule` config seems to have been invalid
because "4 am" had space between "4" and "am" (this was fixed in the
`slsa-verifier` repo on
slsa-framework/slsa-verifier#727 but was never
fixed here).

Also adds a pre-submit to run the
[`renovate-config-validator`](https://docs.renovatebot.com/config-validation/)
to ensure that renovate config is valid. This pre-submit will need to be
made required in the repository branch protection rule for `main` in the
repository settings after this PR is merged.

Fixes #3634 #404 

## Testing Process

- Run `make renovate-config-validator` to check that the config is
valid.

## Checklist

- [x] Review the contributing
[guidelines](https://github.com/slsa-framework/slsa-github-generator/blob/main/CONTRIBUTING.md)
- [x] Add a reference to related issues in the PR description.
- [x] Update documentation if applicable.
- [x] Add unit tests if applicable.
- [x] Add changes to the
[CHANGELOG](https://github.com/slsa-framework/slsa-github-generator/blob/main/CHANGELOG.md)
if applicable.

---------

Signed-off-by: Ian Lewis <ianlewis@google.com>
Signed-off-by: Ramon Petgrave <32398091+ramonpetgrave64@users.noreply.github.com>
Co-authored-by: Ramon Petgrave <32398091+ramonpetgrave64@users.noreply.github.com>

.github/workflows/pre-submit.lint.yml

@@ -34,17 +34,16 @@ jobs:
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
       - uses: actions/setup-node@5e21ff4d9bc1a8cf6de233a3057d20ec6b3fb69d # v3.8.1
         with:
-          node-version: 16
+          node-version: 20
       - run: make markdownlint
 
   markdown-toc:
     name: markdown-toc
     runs-on: ubuntu-latest
     steps:
-      - name: Setup Node.js 16
-        uses: actions/setup-node@5e21ff4d9bc1a8cf6de233a3057d20ec6b3fb69d # v3.8.1
+      - uses: actions/setup-node@5e21ff4d9bc1a8cf6de233a3057d20ec6b3fb69d # v3.8.1
         with:
-          node-version: 16
+          node-version: 20
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
       - run: make markdown-toc
       - name: markdown-toc
@@ -118,9 +117,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
-      - env:
-          YAMLLINT_VERSION: "1.26.3"
-        run: |
+      - run: |
           set -euo pipefail
 
           # Install yamllint
@@ -135,9 +132,18 @@ jobs:
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
       - uses: actions/setup-node@5e21ff4d9bc1a8cf6de233a3057d20ec6b3fb69d # v3.8.1
         with:
-          node-version: 16
+          node-version: 20
       - run: make eslint
 
+  renovate-config-validator:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - uses: actions/setup-node@5e21ff4d9bc1a8cf6de233a3057d20ec6b3fb69d # v3.8.1
+        with:
+          node-version: 20
+      - run: make renovate-config-validator
+
   autogen:
     runs-on: ubuntu-latest
     steps:

Makefile

@@ -168,7 +168,7 @@ markdown-toc: node_modules/.installed ## Runs markdown-toc on markdown files.
 #####################################################################
 
 .PHONY: lint
-lint: markdownlint golangci-lint shellcheck eslint yamllint actionlint ## Run all linters.
+lint: markdownlint golangci-lint shellcheck eslint yamllint actionlint renovate-config-validator ## Run all linters.
 
 .PHONY: actionlint
 actionlint: ## Runs the actionlint linter.
@@ -266,6 +266,10 @@ yamllint: ## Runs the yamllint linter.
 		fi; \
 		yamllint --strict -c .yamllint.yaml . $$extraargs
 
+.PHONY: renovate-config-validator
+renovate-config-validator: node_modules/.installed ## Runs renovate-config-validator
+	@npm run renovate-config-validator
+
 ## Maintenance
 #####################################################################