Fix ./test_dependency_versions.sh path on Windows

The script expects a directory path at the beginning of
`${BASH_SOURCE[0]}`, else the following error occurs:

```txt
test_dependency_versions.sh: line 18: cd: test_dependency_versions.sh:
  Not a directory
```

This is because `${BASH_SOURCE[0]%/*}` will return the original
`${BASH_SOURCE[0]}` without a leading path.

This failure in the Linux `test_dependency_versions` job looks like a
fluke, since the previous run succeeded, as did other current runs:

```
WARNING: Download from
https://github.com/bazelbuild/bazel-skylib/releases/download/1.6.0/bazel-skylib-1.6.0.tar.gz
failed: class java.io.IOException GET returned 618 jwt:jwt-not-provided
``

Author: mbland

.bazelci/presubmit.yml

@@ -135,5 +135,4 @@ tasks:
     batch_commands:
     - "set PATH=/usr/bin;%PATH%" #Make sure bash uses msys commands over windows commands. (i.e. find).
     - "bash -lc \"pacman --noconfirm --needed -S libxml2\"" #tests require xmllint
-    - "bash test_dependency_versions.sh"
-
+    - "bash ./test_dependency_versions.sh" # script removes ./ from BASH_SOURCE