`nimble sync` via git missing submodule in package
The new nimble (v0.14.0) seems not correctly cloning submodule in package. See https://github.com/status-im/nim-bearssl as example. The subfolder `csource` is needed for compiling nim-bearssl based project but new nimble failed to clone the submodule. 

nimble v0.14.0

```
$ builder git:(develop) which nimble
/Users/builder/.nimble/bin/nimble

$ builder git:(develop) nimble -v
   Warning: Using project local deps mode
nimble v0.14.0 compiled at 2021-11-10 07:17:58
git hash: 0a23c44cd8d6c7856d5da155a32298bb1a6ca8e9

$ builder git:(develop) ls nimbledeps/pkgs2/bearssl-0.1.5-092c0cd72b36709f153ae495c4ae31b7d07af526/bearssl
cacert.nim certs      decls.nim  errors.nim
```

nimble v0.13.1

```
➜  builder git:(develop) nimble install nimble
   Warning: Using project local deps mode
Downloading https://github.com/nim-lang/nimble using git
  Verifying dependencies for nimble@0.13.1
 Installing nimble@0.13.1
   Building nimble/nimble using c backend
  Success:  nimble installed successfully.

➜  builder git:(develop)  ./nimbledeps/bin/nimble -v
nimble v0.13.1 compiled at 2021-11-10 07:36:24
git hash: d13f3b8ce288b4dc8c34c219a4e050aaeaf43fc9

➜  builder git:(develop) ./nimbledeps/bin/nimble install bearssl
   Warning: Using project local deps mode
Downloading https://github.com/status-im/nim-bearssl using git
  Verifying dependencies for bearssl@0.1.5
 Installing bearssl@0.1.5
   Success: bearssl installed successfully.

➜  builder git:(develop) ls nimbledeps/pkgs/bearssl-0.1.5/bearssl                                          
cacert.nim certs      csources   decls.nim  errors.nim
```
