Remove redundant nightlies convering the same date

[cameel]

Part of ethereum/solidity#9258. Related to #30 (comment).

These are the only cases where there are multiple nightlies with the same date and version:

('2016.9.15',  [('0.4.2',  '6a80511f'), ('0.4.2',  '8a4f8c23')])
('2016.9.17',  [('0.4.2',  '0bc8476a'), ('0.4.2',  '212e0160'), ('0.4.2', '60f432e8'), ('0.4.2', '62f13ad8'), ('0.4.2', 'a78e7794')])

Surprisingly, there are quite a few where the date is the same but versions differ. I did not touch those.

('2017.7.3',   [('0.4.12', '0c7530a8'), ('0.4.13', '6e4e627b')])
('2020.2.18',  [('0.6.3',  '64f9dc35'), ('0.6.4',  'ba9f740a')])
('2018.5.16',  [('0.4.24', '7f965c86'), ('0.4.25', '3897c367')])
('2017.7.31',  [('0.4.14', '22326189'), ('0.4.15', '93f90eb2')])
('2020.6.4',   [('0.6.10', '0ec96337'), ('0.6.9',  '70e62524')])
('2016.10.25', [('0.4.3',  'd190f016'), ('0.4.4',  'f99a418b')])
('2019.3.13',  [('0.5.6',  '9ccd5dfe'), ('0.5.7',  '2da906d9')])
('2020.1.27',  [('0.6.2',  '1bdb409b'), ('0.6.3',  '8809d4bb')])
('2018.9.25',  [('0.4.26', '1b8334e5'), ('0.5.0',  '608f36d7')])
('2020.3.10',  [('0.6.4',  '683ebc8e'), ('0.6.5',  '59071f60')])
('2019.3.26',  [('0.5.7',  'd079cdbf'), ('0.5.8',  'b85fc1a6')])
('2016.9.9',   [('0.4.1',  '79867f49'), ('0.4.2',  '51a98ab8')])
('2019.1.22',  [('0.5.3',  'd87d9a26'), ('0.5.4',  '26c06550')])
('2019.12.10', [('0.5.14', '45aa7a88'), ('0.6.0',  '7244aa01')])
('2017.3.15',  [('0.4.10', 'd134fda0'), ('0.4.11', '0157b86c')])
('2018.12.3',  [('0.5.1',  'a73df9bc'), ('0.5.2',  'e6a01d26')])
('2020.5.14',  [('0.6.8',  'a6d0067b'), ('0.6.9',  '33d8d838')])
('2018.11.13', [('0.5.0',  'ac980fb8'), ('0.5.1',  '74ede87a')])
('2018.9.13',  [('0.4.25', '15c8c0d2'), ('0.4.26', '8b089cc8')])
('2016.11.21', [('0.4.5',  'afda210a'), ('0.4.6',  'aa48008c')])
('2017.1.31',  [('0.4.10', '747db75a'), ('0.4.9',  'f9af2de0')])
('2018.3.7',   [('0.4.21', 'bd7bc7c4'), ('0.4.22', 'b5e804b8')])
('2017.8.24',  [('0.4.16', '78c2dcac'), ('0.4.17', '012d9f79')])
('2020.5.4',   [('0.6.7',  '94f7ffcf'), ('0.6.8',  '1bb07e26')])
('2018.4.19',  [('0.4.23', 'ae834e3d'), ('0.4.24', '27d79906')])
('2019.5.28',  [('0.5.10', 'ff8898b8'), ('0.5.9',  '01b6b680')])
('2017.11.30', [('0.4.19', 'f5a2508e'), ('0.4.20', 'cb16a5d3')])
('2020.4.9',   [('0.6.6',  '605e176f'), ('0.6.7',  'f8aaa83e')])
('2019.2.12',  [('0.5.4',  'f0f34984'), ('0.5.5',  '828255fa')])
('2019.11.14', [('0.5.13', 'd1c6ab8a'), ('0.5.14', '3e04fd6e')])
('2019.4.30',  [('0.5.8',  '0dc461b9'), ('0.5.9',  'b6bcd8a1')])
('2017.10.18', [('0.4.18', 'e854da1a'), ('0.4.19', 'f7ca2421')])
('2019.6.25',  [('0.5.10', '92529068'), ('0.5.11', '1cc84753')])
('2019.10.1',  [('0.5.12', 'cbdc3bc1'), ('0.5.13', '74d2b228')])
('2017.7.6',   [('0.4.13', '40d4ee49'), ('0.4.14', '08dade9f')])
('2017.1.13',  [('0.4.8',  'bde0b406'), ('0.4.9',  '392ef5f4')])
('2020.4.6',   [('0.6.5',  '8451639f'), ('0.6.6',  'e349f4b7')])
('2016.11.22', [('0.4.6',  '3d9a180c'), ('0.4.7',  '1a205ebf')])

I'm attaching the pythonized version of the list of nightlies from bin/ (not including symlinks) in case we need it later to do some more checks: nightlies-2020-07-09.txt