ZSTD compresion with dictionary causes odd errors

When activating the "use_dict" flag in an SChunk instance, storing data leads to errors.

The following code does not execute on my system:

```
import blosc2
import numpy as np

CHUNKSIZE = int(2**12)
NCHUNKS = 5

coptions = blosc2.cparams_dflts.copy()
coptions["codec"] = blosc2.Codec.ZSTD # this is already the default
coptions["use_dict"] = 1

_rng = np.random.default_rng()

def _make_data() -> bytes:
return _rng.random(CHUNKSIZE // 4, dtype=np.float32).tobytes()

data = [_make_data() for x in range(NCHUNKS)]

storage = blosc2.SChunk(
chunksize=CHUNKSIZE, cparams=coptions, dparams=blosc2.dparams_dflts
)

for x in data:
storage.append_data(x)

for index, x in enumerate(data):
assert storage.decompress_chunk(index) == x
```

Instead, it leads to the following `RuntimeError`:

```
Traceback (most recent call last):
File "/home/user/minimal_bug.py", line 26, in
storage.append_data(x)
File "/home/user/env/lib/python3.9/site-packages/blosc2/schunk.py", line 298, in append_data
return super(SChunk, self).append_data(data)
File "blosc2_ext.pyx", line 1105, in blosc2.blosc2_ext.SChunk.append_data
RuntimeError: Could not append the buffer
```

If the above code is run with `coptions["use_dict"] = 0`, it executes successfully.

Do specific flags need to be set for shared dictionary compression to be successful, or does the sizing of stored data have different requirements?

python-blosc2 version: `blosc2==2.3.2`
python version: `3.9.18`
platform: arch linux, conda based python install

使用 python-blosc2 2.3.2 重现所提供的最小脚本，并检查 schunk.py 中的 SChunk.append_data 以及 blosc2_ext.pyx 中的 traceback 路径。确定 use_dict=1 拒绝这些 chunk 的原因，然后验证在启用字典的情况下追加全部五个缓冲区并分别解压每个缓冲区都能成功。

由索引模型根据 Issue 内容生成。