Fix an issue in the Update script

[Derroylo]

The update script checks the wrong location for the update folder, so gpt downloads the update but it will not be applied.

# Check if the update folder exists
if [ -d "update" ]; then
    cd $GPTDIR

    # Move all files from the update folder to the current one and remove it afterwards
    mv update/* .

    # Remove the update folder
    rm -rf update

    # Set execution rights for the shell script
    chmod +x gpt.sh
fi

but it should be

# Check if the update folder exists
if [ -d "$GPTDIR/update" ]; then
    cd $GPTDIR

    # Move all files from the update folder to the current one and remove it afterwards
    mv update/* .

    # Remove the update folder
    rm -rf update

    # Set execution rights for the shell script
    chmod +x gpt.sh
fi

[Derroylo]

Has been fixed with the linked PR