Lint: ioutil is deprecated, I have the power of search and replace

[jannotti]

Should all be obvious updates.

[codecov]

Codecov Report

Merging #4440 (293d2b3) into master (9c6753e) will decrease coverage by 0.01%.
The diff coverage is 3.37%.

@@            Coverage Diff             @@
##           master    #4440      +/-   ##
==========================================
- Coverage   55.23%   55.21%   -0.02%     
==========================================
  Files         398      398              
  Lines       50148    50165      +17     
==========================================
+ Hits        27699    27700       +1     
- Misses      20135    20152      +17     
+ Partials     2314     2313       -1     

Impacted Files	Coverage Δ
cmd/algod/main.go	0.00% <0.00%> (ø)
cmd/algofix/main.go	1.50% <0.00%> (ø)
cmd/algofix/typecheck.go	0.00% <0.00%> (ø)
cmd/algoh/main.go	0.00% <0.00%> (ø)
cmd/catchupsrv/download.go	12.79% <0.00%> (ø)
cmd/catchupsrv/main.go	0.00% <0.00%> (ø)
cmd/goal/account.go	12.62% <0.00%> (ø)
cmd/goal/accountsList.go	0.00% <0.00%> (ø)
cmd/goal/commands.go	10.40% <0.00%> (ø)
cmd/goal/multisig.go	10.00% <0.00%> (ø)
... and 29 more

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[cce]

amazing