GLIBC_2.27 Not found
I'm using centos7 and I see the following message after doing `choosenim update self`. 

`choosenim: /lib64/libc.so.6: version `GLIBC_2.27' not found (required by choosenim)`

Trying to go back to a version that works. 

I see that somehow you can specify the version of choosenim using env variables, but I can't get this to work. 

I've tried:
```
export CHOOSENIM_CHOOSE_VERSION=v0.7.2/choosenim-0.7.2_linux_amd64
export CHOOSENIM_CHOOSE_VERSION=v0.7.2
```