fix: search config file error

[amone-bit]

There have two config files that have same file name and different extention.

And their contents follow.


This is my code.That will produce a problem.I expect the file named "key_map.toml", but viper read the file named "key_map.json"

And that were some error information that viper gived.

So I update the "file.go" to fix the problem.And now work good.

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[github-actions]

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[sagikazarmark]

There is a lot of confusion around how file searching works in Viper right now.

Technically, config type was not supposed to be used when looking for a file, only for encoding.

The problem with this PR is that it breaks loading files without extensions.

Here is a test that breaks with this PR:

	t.Run("find file without extension", func(t *testing.T) {
		fs := afero.NewMemMapFs()

		err := fs.Mkdir(testutil.AbsFilePath(t, "/etc/viper"), 0o777)
		require.NoError(t, err)

		file, err := fs.Create(testutil.AbsFilePath(t, "/etc/viper/config"))
		require.NoError(t, err)

		_, err = file.WriteString(`key: value`)
		require.NoError(t, err)

		file.Close()

		v := New()

		v.SetFs(fs)
		v.AddConfigPath("/etc/viper")
		v.SetConfigType("yaml")

		err = v.ReadInConfig()
		require.NoError(t, err)

		assert.Equal(t, "value", v.Get("key"))
	})

I opened #1795 to start brainstorming on a better solution.