Update some deprecated Starlark function calls

The `ctx.action()` call and friends are now under `ctx.actions.*`.
This patch updates the calls to the new locations. Newer bazel
versions removed the old versions altogether.

Change-Id: I748d056054d13a0385a06c0c94a2283acfdb82af
diff --git a/tools/build_rules/fortran.bzl b/tools/build_rules/fortran.bzl
index 22882ac..9e6e789 100644
--- a/tools/build_rules/fortran.bzl
+++ b/tools/build_rules/fortran.bzl
@@ -59,8 +59,7 @@
 _single_fortran_object = rule(
     attrs = {
         "src": attr.label(
-            single_file = True,
-            allow_files = FileType([".f"]),
+            allow_single_file = [".f"],
         ),
         "cc_libs": attr.label_list(providers = ["cc"]),
         # TODO(Brian): Replace this with something more fine-grained from the