Update tests and CI to python3 (#5095)

Update debugger and test262 tests to python3
Disable CI jobs that need ubuntu-18.04 (EOL) until they are updated

JerryScript-DCO-1.0-Signed-off-by: Máté Tokodi matet@inf.u-szeged.hu

tools/runners/run-test-suite-test262.py

@@ -26,7 +26,7 @@ import util
 def get_platform_cmd_prefix():
     if sys.platform == 'win32':
         return ['cmd', '/S', '/C']
-    return ['python2']  # The official test262.py isn't python3 compatible, but has python shebang.
+    return ['python3']
 
 
 def get_arguments():

tools/runners/test262-harness.py

@@ -402,13 +402,11 @@ class TempFile(object):
             text=self.text)
 
     def write(self, string):
-        os.write(self.file_desc, string)
+        os.write(self.file_desc, string.encode('utf8'))
 
     def read(self):
-        file_desc = file(self.name)
-        result = file_desc.read()
-        file_desc.close()
-        return result
+        with open(self.name, "r", newline='') as file_desc:
+            return file_desc.read()
 
     def close(self):
         if not self.is_closed:
@@ -495,7 +493,7 @@ class TestCase(object):
         self.name = name
         self.full_path = full_path
         self.strict_mode = strict_mode
-        with open(self.full_path, "rb") as file_desc:
+        with open(self.full_path, "r", newline='') as file_desc:
             self.contents = file_desc.read()
         test_record = parse_test_record(self.contents, name)
         self.test = test_record["test"]