Swallow bundler exceptions when running tests

Let's avoid useless output when testing stuff related to Bundler.
:scissors:
[ci skip] Fix Compiler's Github link
[ci skip] add created_at and updated_at to example
document generators hidden_namespaces
config.assets.digests -> config.assets.digest

in Asset Pipeline guide.

[skip ci]
Merge pull request #15456 from jonatack/patch-7

config.assets.digests -> config.assets.digest
Merge branch 'master' of github.com:rails/docrails
Create Changing Columns on migrations guides

[ci skip]
Add Total of grouped items to AR query interface on guides

[ci skip]
Merge pull request #14881 from robin850/patch-19

Swallow bundler exceptions when running tests
Don't change values in `@raw_attributes` during serialization

During `init_with`, the attributes given to the coder will be placed
into `@raw_attributes`. As such, we should read from `@raw_attributes`
when encoding, rather than `@attributes`, which has been type cast.
Merge pull request #15432 from sgrif/sg-coder-type-casting

Don't change values in `@raw_attributes` during serialization
Remove most code related to serialized properties

Nearly completely implemented in terms of custom properties.
`_before_type_cast` now stores the raw serialized string consistently,
which removes the need to keep track of "state". The following is now
consistently true:

- `model.serialized == model.reload.serialized`
- A model can be dumped and loaded infinitely without changing
- A model can be saved and reloaded infinitely without changing
Merge pull request #15435 from sgrif/sg-rm-serialization

Remove most code related to serialized properties
Merge pull request #15459 from maurogeorge/add-total-grouped-items

Add Total of grouped items to Active Record query interface on guides [ci skip]
Remove docs regarding grouping multiple values, as we should avoid
duplicating API reference in guides. Also :scissors: [ci skip]
Merge pull request #15457 from maurogeorge/add-changing-columns

Create Changing Columns on migrations guides [ci skip]
:nail_care: for migrations guide from #15457 [ci skip]
Detect in-place changes on mutable attributes on Active Model

We have several mutable types on Active Record now. (Serialized, JSON,
HStore). We need to be able to detect if these have been modified in
place. By storing the hashed value of the original attribute, we can
achieve this without significantly increasing memory usage or time for
dirty checking per-record.