Installation error
I am trying to install on Ubuntu 20.04.
```
$ make PREFIX=/usr                                                                                                                                                                                     nim c -d:versionGit -d:release -d:pathext:/usr/share/taskopen/scripts -d:editor:vi -d:open:run-mailcap --outdir:./ src/taskopen.nim
Hint: used config file '/etc/nim/nim.cfg' [Conf]
Hint: system [Processing]
Hint: widestrs [Processing]
Hint: io [Processing]
Hint: taskopen [Processing]
Hint: parseopt [Processing]
Hint: os [Processing]
Hint: strutils [Processing]
Hint: parseutils [Processing]
Hint: math [Processing]
Hint: bitops [Processing]
Hint: macros [Processing]
Hint: algorithm [Processing]
Hint: unicode [Processing]
Hint: pathnorm [Processing]
Hint: osseps [Processing]
Hint: posix [Processing]
Hint: times [Processing]
Hint: options [Processing]
Hint: typetraits [Processing]
Hint: distros [Processing]
Hint: osproc [Processing]
Hint: strtabs [Processing]
Hint: hashes [Processing]
Hint: streams [Processing]
Hint: cpuinfo [Processing]
Hint: linux [Processing]
Hint: tables [Processing]
Hint: output [Processing]
Hint: terminal [Processing]
Hint: strformat [Processing]
Hint: colors [Processing]
Hint: termios [Processing]
Hint: json [Processing]
Hint: lexbase [Processing]
Hint: parsejson [Processing]
Hint: re [Processing]
Hint: pcre [Processing]
Hint: rtarrays [Processing]
Hint: types [Processing]
Hint: exec [Processing]
DIRPATH/taskopen/src/exec.nim(12, 19) Error: type mismatch: got <string, env: StringTableRef>
but expected one of: 
proc execCmdEx(command: string;
              options: set[ProcessOption] = {poStdErrToStdOut, poUsePath}): tuple[
    output: TaintedString, exitCode: int]
  first type mismatch at position: 2
  unknown named parameter: env

expression: execCmdEx(cmd, env = env)
make: *** [Makefile:28: taskopen] Error 1
```

My shell is bash.
