Remove void return type when running tests on PHP 7.0

The void return type was implemented in PHP 7.1 and PHP 7.0 treats the
void return type as a class name.

Errors:
    1) CurlTest\CurlTest::testExtensionsLoaded
    TypeError: Return value of CurlTest\CurlTest::setUp() must be an instance of CurlTest\void, none returned

    /home/runner/work/php-curl-class/php-curl-class/tests/PHPCurlClass/PHPCurlClassTest.php:18

    2) CurlTest\CurlTest::testCaseInsensitiveArrayGet
    TypeError: Return value of CurlTest\CurlTest::setUp() must be an instance of CurlTest\void, none returned

    /home/runner/work/php-curl-class/php-curl-class/tests/PHPCurlClass/PHPCurlClassTest.php:18

    3) CurlTest\CurlTest::testCaseInsensitiveArraySet
    TypeError: Return value of CurlTest\CurlTest::setUp() must be an instance of CurlTest\void, none returned

    /home/runner/work/php-curl-class/php-curl-class/tests/PHPCurlClass/PHPCurlClassTest.php:18

    [...]

Author: zachborboa

tests/ci.sh

@@ -24,6 +24,14 @@ phpunit_v8_1_shim() {
     remove_expectWarning
 }
 
+php_v7_0_shim() {
+    # -protected function setUp(): void
+    # +protected function setUp()
+    find='protected function setUp(): void'
+    replace='protected function setUp()'
+    sed -i'' -e"s/${find}/${replace}/" "./PHPCurlClass/PHP"*
+}
+
 set -x
 
 composer self-update
@@ -76,6 +84,10 @@ elif [[ "${phpunit_version}" == "8.1."* ]]; then
     phpunit_v8_1_shim
 fi
 
+if [[ "${CI_PHP_VERSION}" == "7.0" ]]; then
+    php_v7_0_shim
+fi
+
 # Run tests.
 "${phpunit_to_use}" --version
 "${phpunit_to_use}" \

tests/run.sh

@@ -24,6 +24,14 @@ phpunit_v8_1_shim() {
     remove_expectWarning
 }
 
+php_v7_0_shim() {
+    # -protected function setUp(): void
+    # +protected function setUp()
+    find='protected function setUp(): void'
+    replace='protected function setUp()'
+    sed -i'' -e"s/${find}/${replace}/" "./PHPCurlClass/PHP"*
+}
+
 set -x
 
 # Use composer's phpunit and phpcs by adding composer bin directory to the path environment variable.
@@ -73,6 +81,10 @@ elif [[ "${phpunit_version}" == "8.1."* ]]; then
     phpunit_v8_1_shim
 fi
 
+if [[ "${CI_PHP_VERSION}" == "7.0" ]]; then
+    php_v7_0_shim
+fi
+
 # Run tests.
 extra_args="${@}"
 "${phpunit_to_use}" --version