minor #50427 [VarDumper] Fix failures on appveyor (nicolas-grekas)

This PR was merged into the 6.3 branch.

Discussion
----------

[VarDumper] Fix failures on appveyor

| Q             | A
| ------------- | ---
| Branch?       | 6.3
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

Commits
-------

52f45a4062 [VarDumper] Fix failures on appveyor

Author: nicolas-grekas

Tests/Dumper/functions/dd_with_multiple_args.phpt

@@ -2,6 +2,7 @@
 Test dd() with multiple args shows line number
 --FILE--
 <?php
+putenv('NO_COLOR=1');
 
 $vendor = __DIR__;
 while (!file_exists($vendor.'/vendor')) {

Tests/Dumper/functions/dd_with_null.phpt

@@ -2,6 +2,7 @@
 Test dd() with null doesn't show line number
 --FILE--
 <?php
+putenv('NO_COLOR=1');
 
 $vendor = __DIR__;
 while (!file_exists($vendor.'/vendor')) {

Tests/Dumper/functions/dd_with_single_arg.phpt

@@ -2,6 +2,7 @@
 Test dd() with one arg doesn't show line number
 --FILE--
 <?php
+putenv('NO_COLOR=1');
 
 $vendor = __DIR__;
 while (!file_exists($vendor.'/vendor')) {

Tests/Dumper/functions/dump_with_multiple_args.phpt

@@ -2,6 +2,7 @@
 Test dump() with multiple args shows line number
 --FILE--
 <?php
+putenv('NO_COLOR=1');
 
 $vendor = __DIR__;
 while (!file_exists($vendor.'/vendor')) {

Tests/Dumper/functions/dump_with_null.phpt

@@ -2,6 +2,7 @@
 Test dump() with null doesn't show line number
 --FILE--
 <?php
+putenv('NO_COLOR=1');
 
 $vendor = __DIR__;
 while (!file_exists($vendor.'/vendor')) {

Tests/Dumper/functions/dump_with_single_arg.phpt

@@ -2,6 +2,7 @@
 Test dump() with one arg doesn't show line number
 --FILE--
 <?php
+putenv('NO_COLOR=1');
 
 $vendor = __DIR__;
 while (!file_exists($vendor.'/vendor')) {