Add missing test dependency for Python 3.13

Python 3.13 no longer ships the cgi module. But as we are pinning dependencies on the oldest Python version we support, the corresponding legacy module is not pulled in automatically. So we need to declare it explicitly for the tests for Python 3.13 to have it available.

Author: matthias-bach-by

requirements.in

@@ -6,3 +6,4 @@ pytest-cov
 pytest-mock
 mock
 devpi-plumber[test]>=0.4.3
+legacy-cgi

requirements.txt

@@ -89,6 +89,8 @@ lazy==1.6
     # via
     #   devpi-common
     #   devpi-server
+legacy-cgi==2.6.4
+    # via -r requirements.in
 mock==5.2.0
     # via -r requirements.in
 nh3==0.2.21