Revert commits trying to fix wxWebRequest tests under Wine

This reverts commits 7d796c6aa6 (Install python3 and pip for httpbin,
2021-06-27) and 3808e6a28d (Install winbind package required for using
wxWebRequest with Wine, 2021-06-28) as we skip wxWebRequest tests anyhow
under Wine because they don't work with its WinHTTP implementation, so
running httpbin is not necessary any longer and so neither is installing
Python.

These commits are still preserved in history and this commit itself
could be reverted later if Wine WinHTTP becomes functional enough to run
wxWebRequest tests successfully.

.github/workflows/ci_msw_cross.yml

@@ -86,7 +86,7 @@ jobs:
         run: |
           export DEBIAN_FRONTEND=noninteractive
 
-          packages="git make python3 python3-pip winbind wine x11-xserver-utils xvfb"
+          packages="git make wine x11-xserver-utils xvfb"
 
           case "${HOST_TRIPLET}" in
             x86_64-w64-mingw32)
@@ -193,10 +193,6 @@ jobs:
       - name: Run non-GUI tests
         working-directory: tests
         run: |
-          . ../build/tools/httpbin.sh
-
-          httpbin_launch
-
           # Some tests are currently failing under Wine while they pass under
           # native MSW, just skip running them until they can be dealt with.
 
@@ -219,12 +215,7 @@ jobs:
           # Wine WinHTTP implementations seems buggy, there are many errors.
           excluded_tests+=('~[webrequest]')
 
-          $wxTEST_RUNNER ./test "${excluded_tests[@]}" || rc=$?
-
-          if [ -n "$rc" ]; then
-            httpbin_show_log
-            exit $rc
-          fi
+          $wxTEST_RUNNER ./test "${excluded_tests[@]}"
 
       - name: Run GUI tests
         working-directory: tests