Remove f-strings in python sources

Author: Pavel Marek

com.oracle.truffle.r.test.packages/pkgtest/util.py

@@ -251,7 +251,7 @@ def computeApiChecksum(includeDir):
             with open(fileName) as f:
                 fileContent = f.read().encode()
                 m.update(fileContent)
-                logging.log(VERY_VERBOSE, f"{m.hexdigest()} is checksum after updating with {fileName}")
+                logging.log(VERY_VERBOSE, "{0} is checksum after updating with {1}".format(m.hexdigest(), fileName))
         except IOError as e:
             # Ignore errors on broken symlinks
             if not os.path.islink(fileName) or os.path.exists(fileName):

mx.fastr/mx_fastr.py

@@ -899,7 +899,7 @@ def build_binary_pkgs(args_in, **kwargs):
     finally:
         sys.stdout = sys.__stdout__
     checksum_lines = string_io.getvalue().splitlines(keepends=False)
-    mx.log(f"===== Output of 'mx r-pkgcache --print-api-checksum --vm fastr': =====")
+    mx.log("===== Output of 'mx r-pkgcache --print-api-checksum --vm fastr': =====")
     mx.log(string_io.getvalue())
     mx.log("===== End of output of 'mx r-pkgcache --print-api-checksum --vm fastr' =====")
     with open(os.path.join(pkgs_path, 'api-checksum.txt'), 'w') as f: