powershell: add maintainer script getHashes

pkgs/shells/powershell/getHashes.sh

@@ -0,0 +1,36 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -i bash -p bash wget coreutils gnutar nix
+version=$1
+
+if [[ -z $version ]]
+then
+    echo "Pass the version to get hashes for as an argument"
+    exit 1
+fi
+
+allOutput=""
+
+dlDest=$(mktemp)
+exDest=$(mktemp -d)
+
+trap 'rm $dlDest; rm -r $exDest' EXIT
+
+for plat in osx linux; do
+    for arch in x64 arm64; do
+
+        URL="https://github.com/PowerShell/PowerShell/releases/download/v$version/powershell-$version-$plat-$arch.tar.gz"
+        wget $URL -O $dlDest >&2
+
+        tar -xzf $dlDest -C $exDest >&2
+
+        hash=$(nix hash path $exDest)
+
+        allOutput+="
+variant: $plat $arch
+hash: $hash
+"
+
+    done
+done
+
+echo "$allOutput"