fix: make ExecutionInfo pass under Bazel 5.4

Bazel 5.4 doesn't support the `exec_group` arg. To fix, don't pass that
arg or assert for it in the tests.

Work towards #11
diff --git a/tests/truth_tests.bzl b/tests/truth_tests.bzl
index b8d31b9..713294d 100644
--- a/tests/truth_tests.bzl
+++ b/tests/truth_tests.bzl
@@ -19,6 +19,8 @@
 load("//lib:analysis_test.bzl", "analysis_test", "test_suite")
 load("//lib:util.bzl", "util")
 
+_IS_BAZEL_6_OR_HIGHER = (testing.ExecutionInfo == testing.ExecutionInfo)
+
 _suite = []
 
 _TEST_FILES_ATTR = {
@@ -774,7 +776,8 @@
     subject = truth.expect(fake_env).that_target(target).provider(testing.ExecutionInfo)
     subject.requirements().contains_exactly({"EIKEY1": "EIVALUE1"})
     _assert_no_failures(fake_env, env = env)
-    subject.exec_group().equals("THE_EXEC_GROUP")
+    if _IS_BAZEL_6_OR_HIGHER:
+        subject.exec_group().equals("THE_EXEC_GROUP")
     _assert_no_failures(fake_env, env = env)
     _end(env, fake_env)
 
@@ -1333,6 +1336,11 @@
         ],
         mnemonic = "Action1",
     )
+    if _IS_BAZEL_6_OR_HIGHER:
+        exec_info_bazel_6_kwargs = {"exec_group": "THE_EXEC_GROUP"}
+    else:
+        exec_info_bazel_6_kwargs = {}
+
     return [
         DefaultInfo(
             default_runfiles = ctx.runfiles(
@@ -1346,7 +1354,7 @@
             environment = {"EKEY1": "EVALUE1", "EKEY2": "EVALUE2"},
             inherited_environment = ["INHERIT1", "INHERIT2"],
         ),
-        testing.ExecutionInfo({"EIKEY1": "EIVALUE1"}, exec_group = "THE_EXEC_GROUP"),
+        testing.ExecutionInfo({"EIKEY1": "EIVALUE1"}, **exec_info_bazel_6_kwargs),
         OutputGroupInfo(
             some_group = depset([_empty_file(ctx, "output_group_file.txt")]),
         ),