vendor: replace go-git package

vendor/github.com/go-git/go-billy/v5/osfs/os_posix.go

@@ -0,0 +1,27 @@
+// +build !plan9,!windows
+
+package osfs
+
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+func (f *file) Lock() error {
+	f.m.Lock()
+	defer f.m.Unlock()
+
+	return unix.Flock(int(f.File.Fd()), unix.LOCK_EX)
+}
+
+func (f *file) Unlock() error {
+	f.m.Lock()
+	defer f.m.Unlock()
+
+	return unix.Flock(int(f.File.Fd()), unix.LOCK_UN)
+}
+
+func rename(from, to string) error {
+	return os.Rename(from, to)
+}