test/py: fix typo in test_efi_loader.py

Make a comment line easier to read.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>

test/py/tests/test_efi_loader.py

@@ -12,7 +12,7 @@ import u_boot_utils
 
 """
 Note: This test relies on boardenv_* containing configuration values to define
-which the network environment available for testing. Without this, the parts
+which network environment is available for testing. Without this, the parts
 that rely on network will be automatically skipped.
 
 For example: