run the command xattr -r -d com.apple.quarantine path-to-app in the terminal, where path-to-app is replaced with the path to the .app file (this can be achieved by dragging the app into the terminal)
if it's because it's not a recognized developer then instead of double clicking to open instead right-click and then click Open, it will still say the developer is unrecognized but you will be given the option to open it anyway
