fix: resolve Go test failures in 2019 and 2024 (#9)

* fix: resolve Go test failures in 2019 and 2024

- Remove unused 'errors' import in 2024/golang/cmd/04.go
- Add filepath parameter to readCommands() function in 2019/go/cmd/15
  to match test expectations

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix: replace deprecated drain_filter with stable alternative in 2021/_4

- Remove unstable feature flag #![feature(drain_filter)]
- Replace drain_filter with iter_mut + retain pattern
- All Rust tests in 2021 now compile and pass

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: markkovari

2019/go/cmd/15/main.go

@@ -6,9 +6,9 @@ import (
 	"strings"
 )
 
-func readCommands() ([]int, error) {
+func readCommands(filepath string) ([]int, error) {
 
-	content, err := os.ReadFile("cmd/15/input.data")
+	content, err := os.ReadFile(filepath)
 	if err != nil {
 		return []int{}, err
 	}
@@ -27,7 +27,7 @@ func readCommands() ([]int, error) {
 }
 func main() {
 
-	nums, err := readCommands()
+	nums, err := readCommands("cmd/15/input.data")
 	if err != nil {
 		println("was not able to read")
 	}

2021/_4/src/main.rs

@@ -1,4 +1,3 @@
-#![feature(drain_filter)]
 use std::num::ParseIntError;
 use std::str::FromStr;
 
@@ -129,12 +128,8 @@ fn main() {
     let mut found_table_indicies: Vec<usize> = vec![];
     // let tables_length = tables.len();
     for number in choosen_numbers.0 {
-        tables = tables
-            .drain_filter(|table| {
-                table.toggle(number);
-                table.found_full()
-            })
-            .collect();
+        tables.iter_mut().for_each(|table| table.toggle(number));
+        tables.retain(|table| !table.found_full());
         // tables.retain(|table| (*table).found_full())
     }
     // tables.retain(|table| {

2024/golang/cmd/04.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"bufio"
-	"errors"
 	"fmt"
 	"os"
 	"strings"