Small fix to magic number error printing

[topolarity]

before:

ERROR: MagicMismatch("Magic Number 0x648610 does not match expected PE magic number 0x")

after:

ERROR: MagicMismatch("Magic Number 0x64860100 does not match expected PE magic number 0x50450000")

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.27%. Comparing base (427b624) to head (9ab9cbf).
⚠️ Report is 10 commits behind head on master.

Files with missing lines	Patch %	Lines
src/MachO/MachOHeader.jl	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #53      +/-   ##
==========================================
+ Coverage   68.09%   70.27%   +2.18%     
==========================================
  Files          46       46              
  Lines        1332     1386      +54     
==========================================
+ Hits          907      974      +67     
+ Misses        425      412      -13     

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[giordano]

How....did this ever work 😕 I guess it never did. Also in v0.6, when this line

ObjectFile.jl/src/COFF/COFFHandle.jl

Line 53 in 058bdba

magic number 0x$(join("", hex.(PE_magic)))

was written, it gave the wrong result:

julia> join("", hex.(UInt8['P','E','\0','\0']))
""