Fix warnings in CommandBasedTests

[marciniwanicki]

Describe your changes

• Fix the warnings in CommandBasedTests while building on macOS 10.15.

warning: 'scanString(_:into:)' was deprecated in macOS 10.15
        guard scanString(string, into: result) else {
              ^
warning: 'scanUpToCharacters(from:into:)' was deprecated in macOS 10.15
        guard scanUpToCharacters(from: characterSet, into: result) else {
              ^
warning: 'scanUpToCharacters(from:into:)' was deprecated in macOS 10.15
        guard scanUpToCharacters(from: characterSet, into: result) else {
              ^
warning: 'scanUpTo(_:into:)' was deprecated in macOS 10.15
        guard scanUpTo(string, into: result) else {
              ^
warning: 'scanInt32' was deprecated in macOS 10.15
        guard scanInt32(result) else {

• Removed scanCharactersOrFail method as it was not used

Testing performed

• Inspect the build output to verify there is no warnings

[codecov]

Codecov Report

Merging #76 (2ea3b99) into main (7a1e8a9) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #76   +/-   ##
=======================================
  Coverage   96.13%   96.13%           
=======================================
  Files          47       47           
  Lines        1809     1809           
=======================================
  Hits         1739     1739           
  Misses         70       70           

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