Remove conditional dependence on rich

As this is a python package, we now do rely on rich.

src/mpsd_software_manager/mpsd_software.py

@@ -20,14 +20,7 @@ import importlib.metadata
 
 __version__ = importlib.metadata.version(__package__ or __name__)
 
-# If 'rich' is available ("pip install rich" or "apt-get install python3-rich"),
-# then use coloured output, otherwise proceed as before
-try:
-    import rich.logging
-except ModuleNotFoundError:
-    rich_available = False
-else:
-    rich_available = True
+import rich.logging
 
 command_name = Path(sys.argv[0]).name
 
@@ -246,8 +239,7 @@ def set_up_logging(loglevel="warning", file_path=None):
 
     1. log = logging.getLogger('')
 
-       This is the 'root' logger. It uses a RichHandler if rich is available for
-       output to the shell, otherwise plain text.
+       This is the 'root' logger.
 
        Typical use:
 
@@ -294,19 +286,13 @@ def set_up_logging(loglevel="warning", file_path=None):
     logger.setLevel(0)
 
     # the handler determines where the logs go: stdout/file
-    if rich_available:
-        # https://rich.readthedocs.io/en/stable/logging.html
-        shell_handler = rich.logging.RichHandler()
-        # rich handler provides metadata automatically:
-        logging_format = "%(message)s"
-        # for shell output, only show time (not date and time)
-        shell_formatter = logging.Formatter(logging_format, datefmt="[%X]")
-    else:
-        shell_handler = logging.StreamHandler()
-        # include line numbers in output if level is DEBUG
-        linenumbers = " %(lineno)4d" if log_level_numeric == logging.DEBUG else ""
-        logging_format = "%(asctime)s %(levelname)7s" + linenumbers + "  |  %(message)s"
-        shell_formatter = logging.Formatter(logging_format)
+    # We use 'rich' to provide a Handler:
+    # https://rich.readthedocs.io/en/stable/logging.html
+    shell_handler = rich.logging.RichHandler()
+    # rich handler provides metadata automatically:
+    logging_format = "%(message)s"
+    # for shell output, only show time (not date and time)
+    shell_formatter = logging.Formatter(logging_format, datefmt="[%X]")
 
     # here we hook everything together
     shell_handler.setFormatter(shell_formatter)
@@ -355,8 +341,7 @@ def set_up_logging(loglevel="warning", file_path=None):
     # short message
     #
     logging.debug(
-        f"Logging has been setup, loglevel={loglevel.upper()} "
-        + f"{file_path=} {rich_available=}"
+        f"Logging has been setup, loglevel={loglevel.upper()} " + f"{file_path=}"
     )