Error: can't find file 'markdown'

**shards install**
```
Resolving dependencies
Fetching https://github.com/f/kamber-theme-default.git
Fetching https://github.com/sdogruyol/kemal.git
Fetching https://github.com/luislavena/radix.git
Fetching https://github.com/jeromegn/kilt.git
Shard "kilt" version (0.1.0) doesn't match tag version (0.3.3)
Using radix (0.3.8)
Using kilt (0.3.3)
Using kemal (0.18.3)
Using kamber-theme-default (0.1.0 at f15d186)
```

**crystal build --release src/kamber.cr
./kamber**

```Showing last frame. Use --error-trace for full trace.

In src/kamber.cr:3:1

3 | require "markdown"
^
Error: can't find file 'markdown'

If you're trying to require a shard:
- Did you remember to run `shards install`?
- Did you make sure you're running the compiler in the same directory as your shard.yml?
bash: ./kamber: No such file or directory

```