为什么 tesseract 包不可用？

Question

每次我尝试使用 pkg install tesseract 安装 Tesseract 时，总是说：

Checking availability of current mirror: ok
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Package tesseract is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'tesseract' has no installation candidate```