Conference-app-2020: Text color in About page does not consider dark mode

[nashcft]

Overview (Required)

textColor for the texts in About page refers directly to color resources, so their color does not change according to the change of the app's theme.

Steps To Reproduce

1. Go to 'Settings'
2. Set theme to 'Dark'
3. Go to 'About'

Expected behavior

Text color should be changed corresponding to selected color theme; i.e. use theme's color attribute for the value of textColor.

Screenshots

| Light | Dark |
| -- | -- |
| | |

Env:

• Device: Pixel3
• OS: 10
• App Version or the branch [e.g. 0.1.0 or master]: master

[takahirom]

Thanks for reporting!

[clockvoid]

I could fix it.
The color of version number text was not destined, so I use white in dark mode.
May I make PR with this result?

| Light | Dark |
| ----- | ----- |
| | |

[takahirom]

@clockvoid 🙆