vagrant: pyenv: only use Python 3.11.11

Installing 3.9/10/12 involves downloading and compiling these,
which takes a lot of time and has some potential breaking the
boxes by installing misc. openssl versions.

We test misc. python versions on github actions CI all the time,
so we only need the one here which we want to use for the binary
builds.

Vagrantfile

@@ -167,10 +167,7 @@ end
 def install_pythons(boxname)
   return <<-EOF
     . ~/.bash_profile
-    pyenv install 3.12.0  # tests
     pyenv install 3.11.11  # tests, binary build
-    pyenv install 3.10.2  # tests
-    pyenv install 3.9.4  # tests
     pyenv rehash
   EOF
 end
@@ -235,8 +232,8 @@ def run_tests(boxname, skip_env)
     . ../borg-env/bin/activate
     if which pyenv 2> /dev/null; then
       # for testing, use the earliest point releases of the supported python versions:
-      pyenv global 3.9.4 3.10.2 3.11.11 3.12.0
-      pyenv local 3.9.4 3.10.2 3.11.11 3.12.0
+      pyenv global 3.11.11
+      pyenv local 3.11.11
     fi
     # otherwise: just use the system python
     # avoid that git complains about dubious ownership if we use fakeroot: