List of Python versions
JavaScript (ES6),  128 125  124 bytes
Saved 1 bytes thanks to @OlivierGrégoire
Outputs each version on a separate line. Ordered from highest to lowest major version, and from lowest to highest revision.

f=(r=v=28)=&gt;v?r&lt;parseInt('0111131000244655ah002678b8940'[v],36)?(1+v/10).toFixed(1)+(r|v&gt;22?'.'+r:'')+`
`+f(r+1):f(+!v--):''

Try it online!
How?
The major and minor versions are held in the variable \$v \in [0..27]\$:

major = \$\lfloor v/10+1\rfloor\$
minor = \$v \bmod 10\$

The revision is held in the variable \$r\ge0\$. The maximum value of \$r\$ depends on \$v\$ and is stored in a lookup table encoded in Base-36. Any \$0\$ in this table means that this version was not released at all.
Besides, we use the test \$v&gt;22\$ to know whether the revision should be included even when it's \$0\$ (starting with Python 3.3.0).