Remove last newline from config file (#26468)

When users put the secrets into a file (GITEA__sec__KEY__FILE), the
newline sometimes is different to avoid (eg: echo/vim/...)

So the last newline could be removed when reading, it makes the users
easier to maintain the secret files.

Co-authored-by: Giteabot <teabot@gitea.io>

modules/setting/config_env.go

@@ -4,6 +4,7 @@
 package setting
 
 import (
+	"bytes"
 	"os"
 	"regexp"
 	"strconv"
@@ -131,6 +132,11 @@ func EnvironmentToConfig(cfg ConfigProvider, envs []string) (changed bool) {
 				log.Error("Error reading file for %s : %v", envKey, envValue, err)
 				continue
 			}
+			if bytes.HasSuffix(fileContent, []byte("\r\n")) {
+				fileContent = fileContent[:len(fileContent)-2]
+			} else if bytes.HasSuffix(fileContent, []byte("\n")) {
+				fileContent = fileContent[:len(fileContent)-1]
+			}
 			keyValue = string(fileContent)
 		}