Overriding gtest with gmock

How did this work before...

* Added .direnv/ to gitignore

(cherry picked from commit 58e34a2d27)

.gitignore

@@ -47,3 +47,6 @@ result-*
 .DS_Store
 
 flake-regressions
+
+# direnv
+.direnv/

src/libexpr-tests/meson.build

@@ -32,8 +32,8 @@ deps_private += rapidcheck
 gtest = dependency('gtest')
 deps_private += gtest
 
-gtest = dependency('gmock')
-deps_private += gtest
+gmock = dependency('gmock')
+deps_private += gmock
 
 configdata = configuration_data()
 configdata.set_quoted('PACKAGE_VERSION', meson.project_version())