Fix incorrect PropTypes in Header (#123)
Fix incorrect PropTypes in Header (#123)

Declaring an object with a particular shape is done using
`PropTypes.shape`, not `PropTypes.object`.
canonical-websites/build.snapcraft.io,canonical-ols/build.snapcraft.io,canonical-ols/build.snapcraft.io,canonical-websites/build.snapcraft.io,canonical-ols/build.snapcraft.io,canonical-websites/build.snapcraft.io