refactor: refactor file handling and imports

- Change in main.go: Replaced `godotenv.Load(filename)` with `_ = godotenv.Load(filename)`
- Change in main.go: Replaced `godotenv.Overload("/run/drone/env")` with `_ = godotenv.Overload("/run/drone/env")`
- Change in plugin.go: Added import for "io"
- Change in plugin.go: Replaced `ioutil.ReadAll(r)` with `io.ReadAll(r)`

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

main.go

@@ -16,11 +16,11 @@ var (
 func main() {
 	// Load env-file if it exists first
 	if filename, found := os.LookupEnv("PLUGIN_ENV_FILE"); found {
-		godotenv.Load(filename)
+		_ = godotenv.Load(filename)
 	}
 
 	if _, err := os.Stat("/run/drone/env"); err == nil {
-		godotenv.Overload("/run/drone/env")
+		_ = godotenv.Overload("/run/drone/env")
 	}
 
 	app := cli.NewApp()

plugin.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"html"
+	"io"
 	"io/ioutil"
 	"log"
 	"net/http"
@@ -216,7 +217,7 @@ func loadTextFromFile(filename string) ([]string, error) {
 	}
 	defer f.Close()
 	r := bufio.NewReader(f)
-	content, err := ioutil.ReadAll(r)
+	content, err := io.ReadAll(r)
 	if err != nil {
 		return nil, err
 	}