install ruby for zsteg

Author: burturt

src/install-forensics.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
 
 # Install Forensics Tools
-apt-get install -y binwalk steghide outguess exiftool foremost pngcheck
+apt-get install -y binwalk steghide outguess exiftool foremost pngcheck ruby
 gem install zsteg