fix prod secret token generation compatibility

scripts/prepare-prod-secrets.ps1

@@ -11,7 +11,12 @@ $ErrorActionPreference = "Stop"
 
 function New-Base64SecretValue([int]$Bytes = 48) {
   $buffer = [byte[]]::new($Bytes)
-  [System.Security.Cryptography.RandomNumberGenerator]::Fill($buffer)
+  $rng = [System.Security.Cryptography.RandomNumberGenerator]::Create()
+  try {
+    $rng.GetBytes($buffer)
+  } finally {
+    $rng.Dispose()
+  }
   return [Convert]::ToBase64String([Text.Encoding]::UTF8.GetBytes([Convert]::ToBase64String($buffer)))
 }