fix(install.ps1): force TLS 1.2 via ServicePointManager (eightarms.net requires TLS>=1.2)

install.ps1

@@ -14,9 +14,11 @@
     Do not add the install directory to the user PATH.
 
 .EXAMPLE
+    [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
     irm https://eightarms.net/fourbroad/octopus-release/raw/branch/main/install.ps1 | iex
 
 .EXAMPLE
+    [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
     irm https://eightarms.net/fourbroad/octopus-release/raw/branch/main/install.ps1 | iex; Install-Octopus -Version 0.1.3
 #>
 [CmdletBinding()]
@@ -27,6 +29,7 @@ param(
 
 Set-StrictMode -Version Latest
 $ErrorActionPreference = "Stop"
+[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
 
 $APP       = "octopus"
 $REPO      = "fourbroad/octopus-release"