Remove deprecated CentralProcessor serialNumber method

[dbwiddis]

No description provided.

[codecov-io]

Codecov Report

Merging #703 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #703   +/-   ##
=========================================
  Coverage     82.56%   82.56%           
  Complexity      198      198           
=========================================
  Files            28       28           
  Lines          1503     1503           
  Branches        220      220           
=========================================
  Hits           1241     1241           
  Misses          126      126           
  Partials        136      136

Impacted Files	Coverage Δ	Complexity Δ
.../src/main/java/oshi/hardware/CentralProcessor.java	100% <ø> (ø)	0 <0> (ø)	⬇️

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[coveralls]

Coverage remained the same at 90.486% when pulling 63f72e8 on dbwiddis:master into 1eebf38 on oshi:master.