chore: handle Python 3.9 in GitLab runner startup script (fix #1370) (#1372)

## Description

For users on the standard EC2 AMI, the default Python version is 3.9.
This causes the `eip.tftpl` startup script to fail when running the
`https://bootstrap.pypa.io/get-pip.py` script, as it was updated on May
4th, to require Python >= 3.10.

While it's not ideal to support a EOL Python version, we don't have much
of a choice because of how the get-pip script works, and how the
standard AWS AMIs work.

Ideally, we'd just update the default Python version, however this will
apparently break other things reliant on 3.9

<img width="977" height="259" alt="image"
src="https://github.com/user-attachments/assets/e0c8d02b-19bf-4bae-8468-2255bc9e78ac"
/>

See https://docs.aws.amazon.com/linux/al2023/ug/python.html

Fixes #1370

Co-authored-by: Matthias Kay <matthias.kay@hlag.com>

Author: alexruffo-hireborderless

template/eip.tftpl

@@ -1,7 +1,14 @@
 echo 'installing additional software for assigning EIP'
 
 yum install python3 -y
-curl --fail --retry 6 -O https://bootstrap.pypa.io/get-pip.py
+
+# Check if Python version is 3.9, or greater
+if python3 -c 'import sys; exit(0) if sys.version_info >= (3, 10) else exit(1)'; then
+  curl --fail --retry 6 -O https://bootstrap.pypa.io/get-pip.py
+else
+  curl --fail --retry 6 -O https://bootstrap.pypa.io/pip/3.9/get-pip.py
+fi
+
 python3 get-pip.py --user
 export PATH=~/.local/bin:$PATH