[Regression Script] Support older Python versions (#7482)

This removes two uses of f-strings, which are not supported by Python
<3.6.

diff --git a/test/regress/run_regression.py b/test/regress/run_regression.py
index edb45e4bd185f1373703faaf45f8c15b7a6b5f89..6e65a395acd99c13bf1e30334a601e79284e39f4 100755 (executable)
--- a/test/regress/run_regression.py
+++ b/test/regress/run_regression.py
@@ -258,7 +258,7 @@ class DumpTester(Tester):
                 "--parse-only",
                 "-o",
                 "raw-benchmark",
-                f"--output-lang={ext_to_lang[benchmark_info.benchmark_ext]}",
+                "--output-lang={}".format(ext_to_lang[benchmark_info.benchmark_ext]),
             ]
             dump_output, _, _ = run_process(
                 [benchmark_info.cvc5_binary]
@@ -280,7 +280,7 @@ class DumpTester(Tester):
                 command_line_args=benchmark_info.command_line_args
                 + [
                     "--parse-only",
-                    f"--lang={ext_to_lang[benchmark_info.benchmark_ext]}",
+                    "--lang={}".format(ext_to_lang[benchmark_info.benchmark_ext]),
                 ],
                 benchmark_basename=tmpf.name,
                 expected_output="",