chore: add return types to loader.ts (defenseunicorns#1648)

## Description

In support of defenseunicorns#1364, this PR adds typing to previously-untyped
functions.

End to End Test:  <!-- if applicable -->  
(See [Pepr Excellent
Examples](https://github.com/defenseunicorns/pepr-excellent-examples))

## Related Issue

Fixes #
<!-- or -->
Relates to #

## 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
- [ ] 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
- [ ] [Contributor Guide
Steps](https://docs.pepr.dev/main/contribute/#submitting-a-pull-request)
followed

src/fixtures/loader.ts

@@ -6,11 +6,11 @@ import admissionRequestDeletePod from "./data/admission-delete-pod.json";
 import admissionRequestCreateClusterRole from "./data/admission-create-clusterrole.json";
 import admissionRequestCreateDeployment from "./data/admission-create-deployment.json";
 
-export function AdmissionRequestCreateDeployment() {
+export function AdmissionRequestCreateDeployment(): AdmissionRequest<kind.Deployment> {
   return cloneObject<kind.Deployment>(admissionRequestCreateDeployment);
 }
 
-export function AdmissionRequestCreatePod() {
+export function AdmissionRequestCreatePod(): AdmissionRequest<kind.Pod> {
   return cloneObject<kind.Pod>(admissionRequestCreatePod);
 }