Selecting/installing older nim package on FreeBSD

[thindil]

FreeBSD doesn't store older versions of packages. If you want to use an older 
one, you have to build it from ports, install as package and then lock the 
package, so the system will not upgrade it. In your situation, that could be a 
huge overkill. Thus, probably the best option is to build from source, store 
somewhere and then download, so CI doesn't need to rebuild the compiler every 
time.