Update local.toml.example in packages/backend (#228)

### TL;DR

Added new keys for Google and Turnkey integration in `local.toml.example`

### What changed?

- Updated server session secret to empty string
- Added placeholders for google clientId and clientSecret
- Added placeholders for Turnkey API integration (apiBaseUrl, apiPrivateKey, apiPublicKey, defaultOrganizationId)

### How to test?

1. Pull the latest changes
2. Update `local.toml.example` file with actual values.
3. Run the application locally and ensure all services are working correctly.

### Why make this change?

To integrate new services (Google and Turnkey) into the project setup.

---

packages/backend/environments/local.toml.example

@@ -3,7 +3,7 @@
   port = 8000
   gqlPath = "/graphql"
   [server.session]
-    secret = "p4yfpkqnddkui2iw7t6hbhwq74lbqs7bhobvmfhrowoi"
+    secret = ""
     appOriginUrl = "http://localhost:3000"
     trustProxy = false
     domain = "localhost"
@@ -17,6 +17,16 @@
     clientId = ""
     clientSecret = ""
 
+[google]
+  clientId = ""
+  clientSecret = ""
+
+[turnkey]
+  apiBaseUrl = "https://api.turnkey.com"
+  apiPrivateKey = ""
+  apiPublicKey = ""
+  defaultOrganizationId = ""
+
 [registryConfig]
   fetchDeploymentRecordDelay = 5000
   restEndpoint = "http://localhost:1317"