Test improvement

[peter279k]

Changed log

• Add *.cache file to ignore on Git version control.
• Add php-7.3 and php-7.4 version tests on Travis CI build.
• Using composer install on Travis CI build because the composer.lock is not under Git version control.
• Changing into tests/Unit/ folder to load test classes automatically and it defined on autoload-dev block.
• The satooshi/php-coveralls package is deprecated and using php-coveralls/php-coveralls package instead.

[coveralls]

Pull Request Test Coverage Report for Build 40

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 38:	0.0%
Covered Lines:	22
Relevant Lines:	22

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 40

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

---

Totals
Change from base Build 38:	0.0%
Covered Lines:	22
Relevant Lines:	22

---

💛 - Coveralls

[DivineOmega]

Thanks!