chore: encourage return types in function definitions (defenseunicorn…

…s#1364)

## Description

Encourage non-test code to specify return types.

## Related Issue

Hotifx

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [x] Other (security config, docs update, etc)

## Checklist before merging
- [x] Unit,
[Journey](https://github.com/defenseunicorns/pepr/tree/main/journey),
[E2E Tests](https://github.com/defenseunicorns/pepr-excellent-examples),
[docs](https://github.com/defenseunicorns/pepr/tree/main/docs),
[adr](https://github.com/defenseunicorns/pepr/tree/main/adr) added or
updated as needed
- [x] [Contributor Guide
Steps](https://docs.pepr.dev/main/contribute/#submitting-a-pull-request)
followed

Co-authored-by: Case Wylie <[email protected]>

.eslintrc.json

@@ -21,6 +21,15 @@
     "max-statements": ["warn", { "max": 20 }, { "ignoreTopLevelFunctions": true }],
     "no-invalid-this": "warn"
   },
+  "overrides": [
+    {
+      "files": ["*.ts"],
+      "excludedFiles": "*.test.ts",
+      "rules": {
+        "@typescript-eslint/explicit-function-return-type": "warn"
+      }
+    }
+  ],
   "plugins": ["@typescript-eslint"],
   "ignorePatterns": [
     "src/templates",