bug#41057: core-updates: GNOME Weather doesn't start

[sirgazil]

This happens in both master and core-updates, although it seems to fail with a 
different error in the former (see https://issues.guix.gnu.org/39324). It also 
happens in both real machine and virtual machine.


## Steps to reproduce

Assuming you are using the Guix System with GNOME:

1. Go to Activities → Show Applications (nine dots button) → All → Weather


## Expected result

GNOME Weather starts.


## Unexpected result

You see the GNOME Weather application menu loading next to the "Activities" 
button in the GNOME desktop. But, after a few seconds, the application menu 
disappears  and GNOME Weather never starts. 


## Additional information

In my real machine, running GNOME Weather from a terminal fails too with the 
following message:

```
$ gnome-weather 
Unsatisfied dependency: Gdk
```

In a virtual machine, however, GNOME Weather starts when run from a terminal.

In both, real and virtual machines, GNOME Weather starts when run from the 
minishell (press Alt+F2 and enter gnome-weather).


## System information

```
GNOME Weather 3.34.0

$ LANG=C guix describe
Generation 78   May 02 2020 18:00:20    (current)
  guix 7b07852
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: core-updates
    commit: 7b07852ddb334c92bcef69666f21c599f1f0fa79
  sirgazil-x ef6ac93
    repository URL: https://gitlab.com/sirgazil/guix-channel-x.git
    branch: master
    commit: ef6ac9331a7847fdec6f0eb199524b1b755ba0df
```


---
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