Support for specifying same version twice

[nipunn1313]

Hi,

It would be awesome if pyenv-action supported specifying something like

version: 3.8.6, 3.8.6

Currently, the second installation crashes

It can be helpful when using build matrix w/ multiple variables, with something like

matrix:
   py_step1: [3.8.6, 3.7.9]
   py_step2: [3.8.6, 3.7.9]
steps:
  uses: gabrielfalcao/pyenv-action@v7
  with:
    versions: ${{py_step1}}, ${{pystep2}}

I imagine this would be as simple as set uniq'ing the comma separated list of versions before further processing.

Example logs:

Downloading Python-3.8.6.tar.xz...
-> https://www.python.org/ftp/python/3.8.6/Python-3.8.6.tar.xz
Downloading Python-3.8.6.tar.xz...
-> https://www.python.org/ftp/python/3.8.6/Python-3.8.6.tar.xz
Installing Python-3.8.6...
Installing Python-3.8.6...
cp: cannot create regular file '/opt/hostedtoolcache/pyenv_root/1.2.21/x64/versions/3.8.6/bin/python3.8-gdb.py': File exists