Replace most uses of universal_newlines with text

The parameters are equivalent but the latter is better named. Since
Python 3.6 doesn't support text= we use our wrapper to add it in that
place.

This is for subprocess.run.

src/ocrmypdf/_exec/tesseract.py

@@ -99,9 +99,7 @@ def get_languages():
 
     args_tess = ['tesseract', '--list-langs']
     try:
-        proc = run(
-            args_tess, universal_newlines=True, stdout=PIPE, stderr=STDOUT, check=True
-        )
+        proc = run(args_tess, text=True, stdout=PIPE, stderr=STDOUT, check=True)
         output = proc.stdout
     except CalledProcessError as e:
         raise MissingDependencyError(lang_error(e.output)) from e

src/ocrmypdf/subprocess.py

@@ -52,10 +52,15 @@ def run(args, *, env=None, logs_errors_to_stdout=False, **kwargs):
 
     log.debug("Running: %s", args)
     process_log = log.getChild(os.path.basename(program))
-    if sys.version_info < (3, 7) and os.name == 'nt':
-        # Can't use close_fds=True on Windows with Python 3.6 or older
-        # https://bugs.python.org/issue19575, etc.
-        kwargs['close_fds'] = False
+    if sys.version_info < (3, 7):
+        if os.name == 'nt':
+            # Can't use close_fds=True on Windows with Python 3.6 or older
+            # https://bugs.python.org/issue19575, etc.
+            kwargs['close_fds'] = False
+        if 'text' in kwargs:
+            # Convert run(...text=) to run(...universal_newlines=) for Python 3.6
+            kwargs['universal_newlines'] = kwargs['text']
+            del kwargs['text']
 
     stderr = None
     stderr_name = 'stderr' if not logs_errors_to_stdout else 'stdout'
@@ -119,7 +124,7 @@ def get_version(
         proc = run(
             args_prog,
             close_fds=True,
-            universal_newlines=True,
+            text=True,
             stdout=PIPE,
             stderr=STDOUT,
             check=True,