[chore] update dependencies (#4386)

- codeberg.org/gruf/go-bytesize v1.0.3 -> v1.0.4
- codeberg.org/gruf/go-kv/v2 v2.0.6 -> v2.0.7
- codeberg.org/gruf/go-mutexes v1.5.2 -> v1.5.3
- codeberg.org/gruf/go-structr v0.9.7 -> v0.9.8
- codeberg.org/gruf/go-ffmpreg v0.6.8 -> v0.6.9
- github.com/tomnomnom/linkheader HEAD@2018 -> HEAD@2025

all of the above codeberg.org/gruf updates are in preparation for Go1.25, except for bytesize, and also ffmpreg which is a rebuild with the latest version of ffmpeg (v5.1.7)

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4386
Co-authored-by: kim <grufwub@gmail.com>
Co-committed-by: kim <grufwub@gmail.com>

vendor/codeberg.org/gruf/go-mangler/v2/pointer.go

@@ -0,0 +1,81 @@
+package mangler
+
+import (
+	"reflect"
+	"unsafe"
+
+	"codeberg.org/gruf/go-xunsafe"
+)
+
+// derefPointerType returns a Mangler capable of dereferencing
+// and formatting the given pointer type currently in TypeIter{}.
+// note this will fetch a sub-Mangler for resulting value type.
+func derefPointerType(t xunsafe.TypeIter) Mangler {
+	var derefs int
+	var indirects int64
+	rtype := t.Type
+	flags := t.Flag
+
+	// Iteratively dereference pointer types.
+	for rtype.Kind() == reflect.Pointer {
+
+		// Only if this is actual indirect memory do we
+		// perform a derefence, otherwise we just skip over
+		// and increase the dereference indicator, i.e. '1'.
+		if flags&xunsafe.Reflect_flagIndir != 0 {
+			indirects |= 1 << derefs
+		}
+		derefs++
+
+		// Get next elem type.
+		rtype = rtype.Elem()
+
+		// Get next set of dereferenced element type flags.
+		flags = xunsafe.ReflectPointerElemFlags(flags, rtype)
+	}
+
+	// Ensure this is a reasonable number of derefs.
+	if derefs > 4*int(unsafe.Sizeof(indirects)) {
+		return nil
+	}
+
+	// Wrap value as TypeIter.
+	vt := t.Child(rtype, flags)
+
+	// Get value mangler.
+	fn := loadOrGet(vt)
+	if fn == nil {
+		return nil
+	}
+
+	return func(buf []byte, ptr unsafe.Pointer) []byte {
+		for i := 0; i < derefs; i++ {
+			switch {
+			case indirects&1<<i == 0:
+				// No dereference needed.
+				buf = append(buf, '1')
+
+			case ptr == nil:
+				// Nil value, return here.
+				buf = append(buf, '0')
+				return buf
+
+			default:
+				// Further deref ptr.
+				buf = append(buf, '1')
+				ptr = *(*unsafe.Pointer)(ptr)
+			}
+		}
+
+		if ptr == nil {
+			// Final nil val check.
+			buf = append(buf, '0')
+			return buf
+		}
+
+		// Mangle fully deref'd.
+		buf = append(buf, '1')
+		buf = fn(buf, ptr)
+		return buf
+	}
+}