Update quay.io/linuxserver.io/code-server Docker tag to v4.18.0

#### 📖 Summary

replace `powershell` with `powershell-lts` package

#### 📑 Alternate test plan

| Choice | Test Method       |
| :----: | :-----------      |
|        | Custom test       |
|        | No test plan      |

##### Details / Justification

> 💡 Add your test details or justification for missing tests here.

#### 📚 Additional Notes

- fixes #71

Reviewed-on: CodeServer/arkanum#72
Co-authored-by: OCram85 <marco.blessing@googlemail.com>
Co-committed-by: OCram85 <marco.blessing@googlemail.com>

arkanum

@@ -169,7 +169,7 @@ function instPwsh() {
 
   say "Installing PowerShell..." "PowerShell"
   # Install PowerShell
-  sudo -E apt-get install --no-install-recommends -y powershell
+  sudo -E apt-get install --no-install-recommends -y powershell-lts
 
   say "done." "PowerShell"
 }