RenderTemplate using the text/template package, not the html one (#416)

## Description

Apparently, we imported the wrong package, we need to use text no HTML rules.

## Why is this needed

Wrong import, we do not need to escape following HTML rules.
Fixes: #415 

## How Has This Been Tested?
 Unit test


## Checklist:

I have:

- [x] updated the documentation and/or roadmap (if required)
- [x] added unit or e2e tests
- [x] provided instructions on how to upgrade

workflow/template_validator.go

@@ -4,8 +4,8 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
-	"html/template"
 	"io/ioutil"
+	"text/template"
 
 	"github.com/docker/distribution/reference"
 	"github.com/pkg/errors"
@@ -68,7 +68,7 @@ func RenderTemplate(templateID, templateData string, devices []byte) (string, er
 		return "", err
 	}
 
-	t := template.New("workflow-template")
+	t := template.New("workflow-template").Option("missingkey=error")
 	_, err = t.Parse(string(templateData))
 	if err != nil {
 		err = errors.Wrapf(err, errTemplateParsing, templateID)

workflow/template_validator_test.go

@@ -6,7 +6,7 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/google/uuid"
+	"github.com/google/go-cmp/cmp"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -233,34 +233,84 @@ func TestValidateTemplate(t *testing.T) {
 
 func TestRenderTemplate(t *testing.T) {
 	tests := []struct {
-		name          string
-		hwAddress     []byte
-		expectedError func(t *testing.T, err error)
+		name             string
+		hwAddress        []byte
+		templateID       string
+		templateData     string
+		expectedError    func(t *testing.T, err error)
+		expectedTemplate string
 	}{
 		{
-			name:      "valid-hardware-address",
-			hwAddress: []byte("{\"device_1\":\"08:00:27:00:00:01\"}"),
+			name:         "valid-hardware-address",
+			hwAddress:    []byte("{\"device_1\":\"08:00:27:00:00:01\"}"),
+			templateID:   "49748301-d0d9-4ee9-84df-b64e6e1ef3dd",
+			templateData: validTemplate,
+			expectedTemplate: `
+version: "0.1"
+name: hello_world_workflow
+global_timeout: 600
+tasks:
+  - name: "hello world"
+    worker: "08:00:27:00:00:01"
+    actions:
+    - name: "hello_world"
+      image: hello-world
+      timeout: 60
+`,
 		},
 		{
-			name:      "invalid-hardware-address",
-			hwAddress: []byte("{\"invalid_device\":\"08:00:27:00:00:01\"}"),
+			name:         "invalid-hardware-address",
+			templateData: validTemplate,
+			hwAddress:    []byte("{\"invalid_device\":\"08:00:27:00:00:01\"}"),
 			expectedError: func(t *testing.T, err error) {
 				if err == nil {
 					t.Error("expected error, got nil")
 				}
-				if !strings.Contains(err.Error(), "invalid hardware address: {\"invalid_device\":\"08:00:27:00:00:01\"}") {
-					t.Errorf("\nexpected err: %s\ngot: %s", "invalid hardware address: {\"invalid_device\":\"08:00:27:00:00:01\"}", err)
+				if !strings.Contains(err.Error(), `executing "workflow-template" at <.device_1>: map has no entry for key "device_1"`) {
+					t.Errorf("\nexpected err: %s\ngot: %s", `executing "workflow-template" at <.device_1>: map has no entry for key "device_1"`, err)
 				}
 			},
 		},
+		{
+			name:       "template with << should not be escaped in any way",
+			hwAddress:  []byte("{\"device_1\":\"08:00:27:00:00:01\"}"),
+			templateID: "98788301-d0d9-4ee9-84df-b64e6e1ef1cc",
+			templateData: `
+version: "0.1"
+name: hello_world_workflow
+global_timeout: 600
+tasks:
+  - name: "hello world<<"
+    worker: "{{.device_1}}"
+    actions:
+    - name: "hello_world"
+      image: hello-world
+      timeout: 60
+`,
+			expectedTemplate: `
+version: "0.1"
+name: hello_world_workflow
+global_timeout: 600
+tasks:
+  - name: "hello world<<"
+    worker: "08:00:27:00:00:01"
+    actions:
+    - name: "hello_world"
+      image: hello-world
+      timeout: 60
+`,
+		},
 	}
 
-	templateID := uuid.New().String()
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			_, err := RenderTemplate(templateID, validTemplate, test.hwAddress)
-			if err != nil {
+			temp, err := RenderTemplate(test.templateID, test.templateData, test.hwAddress)
+			if test.expectedError != nil {
 				test.expectedError(t, err)
+				return
+			}
+			if diff := cmp.Diff(test.expectedTemplate, temp); diff != "" {
+				t.Error(diff)
 			}
 		})
 	}