Introduce check job for make test

This commit introduces a new Github Workflow named "Unit Tests". This
workflow is responsible for running unit tests triggered by (make
tests).

This commit also addresses the following error that was encountered when
one ran make test locally or in a job:

---
unable to fetch hash for requested version: unable fetch metadata for
kubebuilder-tools-1.30.0-linux-amd64.tar.gz -- got status "401
Unauthorized" from GCS
---

The fixes bumps up the test dependencies (ENVTEST_VERSION release-0.18
-> release-0.22). The previous vrsion was trying to pull the the test
dependencies from GCS server that has been deprecated as part of 0.19
[1].

[1] kubernetes-sigs/controller-runtime#2915

Author: lpiwowar

.github/workflows/unit-tests.yaml

@@ -0,0 +1,21 @@
+name: Unit Tests
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  unit-tests:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v7
+
+      - name: Set up Go
+        uses: actions/setup-go@v6
+
+      - name: Run tests
+        run: make test

Makefile

@@ -246,7 +246,7 @@ KUTTL ?= $(LOCALBIN)/kubectl-kuttl
 ## Tool Versions
 KUSTOMIZE_VERSION ?= v5.4.2
 CONTROLLER_TOOLS_VERSION ?= v0.16.5
-ENVTEST_VERSION ?= release-0.18
+ENVTEST_VERSION ?= release-0.22
 GOLANGCI_LINT_VERSION ?= v2.6.0
 KUTTL_VERSION ?= 0.22.0