Fix release URL when VERSION != latest

Latest download URL is structured differently than version download URL.

install.ps1

@@ -1,7 +1,9 @@
 # check if VERSION env variable is set, otherwise use "latest"
-$VERSION = if ($null -eq $Env:VERSION) { "latest" } else { $Env:VERSION }
-
-$RELEASE_URL="https://github.com/mamba-org/micromamba-releases/releases/$VERSION/download/micromamba-win-64"
+$RELEASE_URL = if ($null -eq $Env:VERSION) {
+    "https://github.com/mamba-org/micromamba-releases/releases/latest/download/micromamba-win-64"
+} else {
+    "https://github.com/mamba-org/micromamba-releases/releases/download/$Env:VERSION/micromamba-win-64"
+}
 
 Write-Output "Downloading micromamba from $RELEASE_URL"
 curl.exe -L -o micromamba.exe $RELEASE_URL
@@ -41,4 +43,4 @@ if ($choice -eq "y" -or $choice -eq "Y" -or $choice -eq "") {
     & $MAMBA_INSTALL_PATH shell init -s powershell -p $prefix
 } else {
     Write-Output "`nYou can always initialize powershell or cmd.exe with micromamba by running `nmicromamba shell init -s powershell -p $Env:UserProfile\micromamba`n"
-}
+}