Added check that ensures that go.mod & go.sum files are up-to-date.
The check verifies whether 'go mod tidy' does not generate any mutations
in these files.
The check can be run on its own:
PASSES="mod_tidy" ./test
Or as part of "fmt" pass:
PASSES="fmt" ./test
Examplar outputs:
```
% PASSES="fmt" ./test
Running with TEST_CPUS: 1,2,4
Starting 'fmt' pass at Fri 11 Sep 2020 11:07:54 PM CEST
'shellcheck' started at Fri 11 Sep 2020 11:07:54 PM CEST
'shellcheck' completed at Fri 11 Sep 2020 11:07:54 PM CEST
'markdown_you' started at Fri 11 Sep 2020 11:07:54 PM CEST
'markdown_you' completed at Fri 11 Sep 2020 11:07:54 PM CEST
'goword' started at Fri 11 Sep 2020 11:07:54 PM CEST
'goword' completed at Fri 11 Sep 2020 11:07:54 PM CEST
'gofmt' started at Fri 11 Sep 2020 11:07:54 PM CEST
'gofmt' completed at Fri 11 Sep 2020 11:07:55 PM CEST
'govet' started at Fri 11 Sep 2020 11:07:55 PM CEST
'govet' completed at Fri 11 Sep 2020 11:07:57 PM CEST
'revive' started at Fri 11 Sep 2020 11:07:57 PM CEST
Skipping revive...
'revive' completed at Fri 11 Sep 2020 11:07:57 PM CEST
'license_header' started at Fri 11 Sep 2020 11:07:57 PM CEST
'license_header' completed at Fri 11 Sep 2020 11:07:58 PM CEST
'receiver_name' started at Fri 11 Sep 2020 11:07:58 PM CEST
'receiver_name' completed at Fri 11 Sep 2020 11:07:58 PM CEST
'commit_title' started at Fri 11 Sep 2020 11:07:58 PM CEST
'commit_title' completed at Fri 11 Sep 2020 11:07:58 PM CEST
'mod_tidy' started at Fri 11 Sep 2020 11:07:58 PM CEST
*** /tmp/fileiALKRA_go.mod 2020-09-11 23:07:58.838010716 +0200
--- ./go.mod 2020-09-11 23:07:58.974010922 +0200
***************
*** 29,39 ****
github.com/mattn/go-runewidth v0.0.2 // indirect
github.com/modern-go/reflect2 v1.0.1
github.com/olekukonko/tablewriter v0.0.0-20170122224234-a0225b3f23b5
github.com/prometheus/client_golang v1.0.0
github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4
- github.com/prometheus/common v0.4.1
github.com/sirupsen/logrus v1.4.2 // indirect
github.com/soheilhy/cmux v0.1.4
github.com/spf13/cobra v0.0.3
github.com/spf13/pflag v1.0.1
github.com/tmc/grpc-websocket-proxy v0.0.0-20170815181823-89b8d40f7ca8
--- 29,38 ----
./go.mod is not in sync with 'go mod tidy'
```
```
% PASSES="mod_tidy" ./test
Running with TEST_CPUS: 1,2,4
Starting 'mod_tidy' pass at Fri 11 Sep 2020 11:09:21 PM CEST
*** /tmp/file9gy4so_go.mod 2020-09-11 23:09:21.166133290 +0200
--- ./go.mod 2020-09-11 23:09:21.286133466 +0200
***************
*** 29,39 ****
github.com/mattn/go-runewidth v0.0.2 // indirect
github.com/modern-go/reflect2 v1.0.1
github.com/olekukonko/tablewriter v0.0.0-20170122224234-a0225b3f23b5
github.com/prometheus/client_golang v1.0.0
github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4
- github.com/prometheus/common v0.4.1
github.com/sirupsen/logrus v1.4.2 // indirect
github.com/soheilhy/cmux v0.1.4
github.com/spf13/cobra v0.0.3
github.com/spf13/pflag v1.0.1
github.com/tmc/grpc-websocket-proxy v0.0.0-20170815181823-89b8d40f7ca8
--- 29,38 ----
./go.mod is not in sync with 'go mod tidy'
```
