Byte misalignment in `bit_vector`

[elshize]

Describe the bug

When running test_bmw_queries, the UB sanitizer reports an error (see below).

To Reproduce
Steps to reproduce the behavior:

1. Compile with sanitizers
2. ./test/test_bmw_queries

Error message

/home/elshize/dev/pisa/include/pisa/bit_vector.hpp:104:16: runtime error: load of misaligned address 0x7fe426d2cd3b for type 'const uint64_t' (aka 'const unsigned long'), which requires 8 byte alignment
0x7fe426d2cd3b: note: pointer points here
 35  89 9e 4e 54 a1 a2 e5 15  55 b8 e8 08 46 58 33 12  b0 11 48 8e ee 75 34 cb  23 78 1f 25 06 e9 75
              ^
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /home/elshize/dev/pisa/include/pisa/bit_vector.hpp:104:16 in

Environment info
Operating System: Fedora
Compiler name: Clang
Compiler version: 15

[elshize]

Duplicate of #444