Prefix .bat file script invocation lines with "call"

Apparently when the Gitlab Runner is using "cmd", you must do this or only
the first invoked bat file is executed. This explains why sbbsctrl.exe
(and other) files have been missing from the CI-generated artifact archives.
Back when I was using "powershell" to invoke the CI build for sbbs-windows
(my Gitlab-runner/config.toml file had shell = "powershell"), this wasn't an
issue, but this configuration stopped working on Vert at some point
(https://forum.gitlab.com/t/windows-10-gitlab-runner-fails-with-error-no-process-is-on-the-other-end-of-the-pipe/66691)
so I switched to "cmd", even though it's deprecated.

Remove the dependencies: [] line since that wasn't a solution to anything.

.gitlab-ci.yml

@@ -55,18 +55,17 @@ sbbs-windows:
     - cd src/xpdev
     - make
     - cd ../../src/sbbs3
-    - .\release.bat
+    - call .\release.bat
     - cd ctrl
-    - .\build.bat
+    - call .\build.bat
     - cd ../chat
-    - .\build.bat
+    - call .\build.bat
     - cd ../useredit
-    - .\build.bat
+    - call .\build.bat
     - cd ../../../xtrn/sbj
     - make
     - cd ../tbd
     - make
-  dependencies: []
   artifacts:
     name: sbbs-win32
     paths: