To reproduce:

git clone git@github.com:python/cpython.git --depth=2
cd Lib/test/cjkencodings
lychee .

Error:

Error: Cannot read input content from file `./big5.txt`

Caused by:
    stream did not contain valid UTF-8

This happens to some legacy CJK files.

This bug was found by @yihong0618

Expect:

lychee should skip those files if it's not valid UTF-8 encoded.