Disable //:ScalafmtTest.format-test on Windows

Works around the following `test_dependency_version.sh` failure:

```txt
FATAL:
  ExecuteProgram(C:\tools\msys64\home\b\_bazel_b\...\ScalafmtTest.format-test)
  failed: ERROR: src/main/native/windows/process.cc(202):
  CreateProcessW("C:\tools\msys64\home\b\_bazel_b\...\ScalafmtTest.format-test"):
  %1 is not a valid Win32 application.
 (error: 193)
  Test "test_precompiled_protoc_rules_java_7" failed  (49 sec)
```

Author: mbland

test_dependency_versions.sh

@@ -154,7 +154,15 @@ do_build_and_test() {
   set -e
   bazel build //...
   bazel test //...
-  bazel run //:ScalafmtTest.format-test
+
+  # Windows fails with:
+  # FATAL: ExecuteProgram(C:\...\ScalafmtTest.format-test) failed:
+  #   ERROR: src/main/native/windows/process.cc(202):
+  #   CreateProcessW("C:\...\ScalafmtTest.format-test"):
+  #   %1 is not a valid Win32 application.
+  if ! is_windows; then
+    bazel run //:ScalafmtTest.format-test
+  fi
 }
 
 test_minimum_supported_versions() {