Fix bug in vectorize of random variables with empty size

[ricardoV94]

Description

Bug left out from when we fixed shape=None != shape=()

Related Issue

• Closes #
• Related to #

Checklist

• Checked that the pre-commit linting/style checks pass
• Included tests that prove the fix is effective or that the new feature works
• Added necessary documentation (docstrings and/or example notebooks)
• If you are a pro: each commit corresponds to a relevant logical change

Type of change

• New feature / enhancement
• Bug fix
• Documentation
• Maintenance
• Other (please specify):

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.00%. Comparing base (31bf682) to head (7673c7a).
Report is 124 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@ ## main #886 +/- ## ========================================== - Coverage 81.00% 81.00% -0.01%  ========================================== Files 170 170 Lines 46923 46922 -1 Branches 11497 11497 ========================================== - Hits 38009 38008 -1  - Misses 6704 6706 +2  + Partials 2210 2208 -2 

Files with missing lines	Coverage Δ
pytensor/tensor/random/op.py	93.75% <100.00%> (-0.04%)	⬇️

... and 2 files with indirect coverage changes