Enable Pylint in CI and fix its errors (#311)

* Remove wildcard imports

Use explicit imports rather than wildcards. This is more maintainable.

* Enable Pylint in CI and fix its errors

The main fixes were:

* Specify encoding for all file opens. By default it depends on environment variables which is bad.
* Use `with` to open files. Otherwise they don't necessarily get closed.

There were also a few minor things like using `enumerate`, not using objects as default arguments, etc. In some cases I slightly refactored the code.

sverilog_utils.py

@@ -1,7 +1,9 @@
 import logging
 import pprint
+from pathlib import Path
 
-from shared_utils import *
+from constants import csrs, csrs32
+from shared_utils import InstrDict
 
 pp = pprint.PrettyPrinter(indent=2)
 logging.basicConfig(level=logging.INFO, format="%(levelname)s:: %(message)s")
@@ -17,13 +19,12 @@ def make_sverilog(instr_dict: InstrDict):
             f"  localparam logic [11:0] CSR_{name.upper()} = 12'h{hex(num)[2:]};\n"
         )
 
-    sverilog_file = open("inst.sverilog", "w")
-    sverilog_file.write(
+    Path("inst.sverilog").write_text(
         f"""
 /* Automatically generated by parse_opcodes */
 package riscv_instr;
 {names_str}
 endpackage
-"""
+""",
+        encoding="utf-8",
     )
-    sverilog_file.close()