Fixing type of env var in cache template

chart/templates/cache-deployment.yaml

@@ -75,7 +75,7 @@ spec:
             - name: WAIT_SERVICES
               value: "{{ .Release.Name }}-database:{{ .Values.config.database.DB_PORT }} {{ .Release.Name }}-renderer:80"
             - name: WAIT_TIMEOUT
-              value: 300
+              value: "300"
           volumeMounts:
             - mountPath: /mapcache-template.xml
               name: cache-config.xml