improve version parser

build/show-powershell-images.ps1

@@ -1,6 +1,4 @@
-#Requires -Version "7.0"
-
-$ErrorActionPreference = "Stop"
+$ErrorActionPreference = 'Stop'
 
 function Get-ShortVersion {
     [CmdletBinding()]
@@ -11,18 +9,27 @@ function Get-ShortVersion {
     )
 
     process {
-        $parts = $FullVersion -split "-"
-        $result = $parts[0]
+        # preview-7.5-ubuntu-20.04
+        # 7.4-ubuntu-22.04
+        # 7.3.0-preview.1-ubuntu-20.04
+        $parts = $FullVersion -split '-'
+        $version = $parts[0]
+        $tag = $parts[1]
+
+        if ($version -like 'preview*') {
+            $version = $parts[1]
+            $tag = $parts[0]
+        }
 
-        if ($parts[1] -like "preview*") {
-            $result += "-" + $parts[1]
+        if ($tag -like 'preview*') {
+            $version += '-' + $tag
         }
 
-        return $result
+        return $version
     }
 }
 
-(Invoke-RestMethod -Uri "https://mcr.microsoft.com/v2/powershell/tags/list").tags `
-    | Where-Object {$_ -Like "[0-9]*"} `
-    | Get-ShortVersion `
-    | Sort-Object -Unique
+(Invoke-RestMethod -Uri 'https://mcr.microsoft.com/v2/powershell/tags/list').tags `
+| Where-Object { ($_ -Like '[0-9]*') -or ($_ -Like 'preview-[0-9]*') } `
+| Get-ShortVersion `
+| Sort-Object -Unique