[trivial] mark download.sh as executable

[jda]

Llama-Guard README.md says:

Then to run the script: ./download.sh

However, download.sh is not marked as executable, so this doesn't work (at least on GNU bash 5.2.15):

jda@tangent:/bulk/datasets/MetaLlama/PurpleLlama/Llama-Guard$ ls -la download.sh
-rw-r--r-- 1 jda jda 947 Mar 11 19:46 download.sh
jda@tangent:/bulk/datasets/MetaLlama/PurpleLlama/Llama-Guard$ ./download.sh
-bash: ./download.sh: Permission denied

But it does work after marking download.sh as executable (chmod 755 download.sh):

jda@tangent:~/Projects/PurpleLlama/Llama-Guard$ ls -la download.sh
-rwxr-xr-x 1 jda jda 947 Mar 11 19:52 download.sh
jda@tangent:~/Projects/PurpleLlama/Llama-Guard$ ./download.sh
Enter the URL from email: ^C

[mbhatt1]

Thanks :)