[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/cache.go

@@ -0,0 +1,62 @@
+package mangler
+
+import (
+	"sync/atomic"
+	"unsafe"
+
+	"codeberg.org/gruf/go-xunsafe"
+)
+
+var manglers cache
+
+// cache is a concurrency-safe map[xunsafe.TypeInfo]Mangler
+// cache, designed for heavy reads but with unfortunately expensive
+// writes. it is designed such that after some initial load period
+// in which functions are cached by types, all future ops are reads.
+type cache struct{ p unsafe.Pointer }
+
+// Get will check cache for mangler func under key.
+func (c *cache) Get(t xunsafe.TypeInfo) Mangler {
+	if p := c.load(); p != nil {
+		return (*p)[t]
+	}
+	return nil
+}
+
+// Put will place given mangler func in cache under key, if not already exists.
+func (c *cache) Put(t xunsafe.TypeInfo, fn Mangler) {
+	for {
+		p := c.load()
+
+		var cache map[xunsafe.TypeInfo]Mangler
+
+		if p != nil {
+			if _, ok := (*p)[t]; ok {
+				return
+			}
+
+			cache = make(map[xunsafe.TypeInfo]Mangler, len(*p)+1)
+			for key, value := range *p {
+				cache[key] = value
+			}
+		} else {
+			cache = make(map[xunsafe.TypeInfo]Mangler, 1)
+		}
+
+		cache[t] = fn
+
+		if c.cas(p, &cache) {
+			return
+		}
+	}
+}
+
+// load is a typed wrapper around atomic.LoadPointer().
+func (c *cache) load() *map[xunsafe.TypeInfo]Mangler {
+	return (*map[xunsafe.TypeInfo]Mangler)(atomic.LoadPointer(&c.p))
+}
+
+// cas is a typed wrapper around atomic.CompareAndSwapPointer().
+func (c *cache) cas(old, new *map[xunsafe.TypeInfo]Mangler) bool {
+	return atomic.CompareAndSwapPointer(&c.p, unsafe.Pointer(old), unsafe.Pointer(new))
+}