Fix: Use FileNotFoundError for file not found in main.py

Replaced IOError with FileNotFoundError on line 377 of main.py to use a more specific and appropriate exception for file not found errors.

test: update test_find_dotenv_no_file_raise to expect FileNotFoundError
Updated test_main.py (line 351) to replace IOError with FileNotFoundError so that the test matches the updated exception handling in main.py.

Author: creepereye1204

src/dotenv/parser.py

@@ -80,15 +80,15 @@ def set_mark(self) -> None:
 
     def get_marked(self) -> Original:
         return Original(
-            string=self.string[self.mark.chars : self.position.chars],
+            string=self.string[self.mark.chars: self.position.chars],
             line=self.mark.line,
         )
 
     def peek(self, count: int) -> str:
-        return self.string[self.position.chars : self.position.chars + count]
+        return self.string[self.position.chars: self.position.chars + count]
 
     def read(self, count: int) -> str:
-        result = self.string[self.position.chars : self.position.chars + count]
+        result = self.string[self.position.chars: self.position.chars + count]
         if len(result) < count:
             raise Error("read: End of string")
         self.position.advance(result)
@@ -98,7 +98,7 @@ def read_regex(self, regex: Pattern[str]) -> Sequence[str]:
         match = regex.match(self.string, self.position.chars)
         if match is None:
             raise Error("read_regex: Pattern not found")
-        self.position.advance(self.string[match.start() : match.end()])
+        self.position.advance(self.string[match.start(): match.end()])
         return match.groups()