date range on NTP Rewards widget v2 is incorrect

[LaurenWags]

Description

Found while testing #17483.

For the month of Nov, date range is listed as Nov 1-Nov 29, but Nov has 30 days.

Steps to Reproduce

1. Clean profile
2. Enable Rewards
3. Look at NTP widget

Actual result:

Date range says Nov 1 - Nov 29:

Expected result:

Should say Nov 1 - Nov 30

Reproduces how often:

easily

Brave version (brave://version info)

Brave	1.33.87 Chromium: 96.0.4664.45 (Official Build) beta (x86_64)
Revision	76e4c1bb2ab4671b8beba3444e61c0f17584b2fc-refs/branch-heads/4664@{#947}
OS	macOS Version 11.6.1 (Build 20G224)

Version/Channel Information:

• Can you reproduce this issue with the current release? n/a
• Can you reproduce this issue with the beta channel? yes
• Can you reproduce this issue with the nightly channel? yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
• Does the issue resolve itself when disabling Brave Rewards?
• Is the issue reproducible on the latest version of Chrome?

Miscellaneous Information:

cc @zenparsing @Miyayes @brave/legacy_qa

[LaurenWags]

QA/Blocked until a new 1.33.x is built (1.33.96 or above)

[LaurenWags]

Removing QA/Blocked, 1.33.98 is available.

[LaurenWags]

Verified passed with

Brave | 1.33.99 Chromium: 96.0.4664.55 (Official Build) (x86_64)
-- | --
Revision | 38cededc5d09b785d12203f1d3209aa6eb293e79-refs/branch-heads/4664@{#1090}
OS | macOS Version 11.6.1 (Build 20G224)

Verified STR from #19691 (comment) for a few different months.
Confirmed date ranges were accurate on the widget.

December	January	February