Add workflow to generate stats for release

[ijjk]

This adds triggering the PR Stats GitHub Action for a canary release. It compares the latest canary release with the last stable release and posts it as a comment to the commit.

[github-actions]

Stats from current PR

Click to expand stats

	zeit/next.js canary	ijjk/next.js add/release-stats	Change
Build Duration	12.2s	11.9s	-305ms
Client _app Size	3.03 kB	3.03 kB	✓
Client _app gzip Size	1.29 kB	1.29 kB	✓
Client _error Size	8.85 kB	8.85 kB	✓
Client _error gzip Size	3.31 kB	3.31 kB	✓
Client pages/index Size	298 B	298 B	✓
Client pages/index gzip Size	235 B	235 B	✓
Client pages/link Size	3.28 kB	3.28 kB	✓
Client pages/link gzip Size	1.49 kB	1.49 kB	✓
Client pages/routerDirect Size	426 B	426 B	✓
Client pages/routerDirect gzip Size	304 B	304 B	✓
Client pages/withRouter Size	408 B	408 B	✓
Client pages/withRouter gzip Size	293 B	293 B	✓
Client main Size	22.1 kB	22.1 kB	✓
Client main gzip Size	7.24 kB	7.24 kB	✓
Client commons Size	182 kB	182 kB	✓
Client commons gzip Size	59.4 kB	59.4 kB	✓
Client webpack Size	1.49 kB	1.49 kB	✓
Client webpack gzip Size	774 B	774 B	✓
Base Rendered Size	1.3 kB	1.3 kB	✓
Build Dir Size	346 kB	346 kB	✓
Average Memory Usage	127 MB	128 MB	⚠️ +599 kB
Max Memory Usage	162 MB	166 MB	⚠️ +3.57 MB
Average CPU Usage	93.01%	93.65%	⚠️ +0.64%
Max CPU Usage	110%	111.11%	⚠️ +1.11%
node_modules Size	42.7 MB	42.7 MB	✓

Click to expand serverless stats

	zeit/next.js canary	ijjk/next.js add/release-stats	Change
Build Duration	14.5s	15.8s	⚠️ +1.3s
Client _app Size	3.03 kB	3.03 kB	✓
Client _app gzip Size	1.29 kB	1.29 kB	✓
Client _error Size	8.85 kB	8.85 kB	✓
Client _error gzip Size	3.31 kB	3.31 kB	✓
Client pages/index Size	298 B	298 B	✓
Client pages/index gzip Size	235 B	235 B	✓
Client pages/link Size	3.28 kB	3.28 kB	✓
Client pages/link gzip Size	1.49 kB	1.49 kB	✓
Client pages/routerDirect Size	426 B	426 B	✓
Client pages/routerDirect gzip Size	304 B	304 B	✓
Client pages/withRouter Size	408 B	408 B	✓
Client pages/withRouter gzip Size	293 B	293 B	✓
Client main Size	22.1 kB	22.1 kB	✓
Client main gzip Size	7.24 kB	7.24 kB	✓
Client commons Size	182 kB	182 kB	✓
Client commons gzip Size	59.4 kB	59.4 kB	✓
Client webpack Size	1.49 kB	1.49 kB	✓
Client webpack gzip Size	774 B	774 B	✓
Serverless pages/link Size	220 kB	220 kB	✓
Serverless pages/link gzip Size	58 kB	58 kB	⚠️ +3 B
Serverless pages/index Size	215 kB	215 kB	✓
Serverless pages/index gzip Size	56.8 kB	56.8 kB	⚠️ +3 B
Serverless pages/_error Size	217 kB	217 kB	✓
Serverless pages/_error gzip Size	56.8 kB	56.8 kB	⚠️ +5 B
Serverless pages/routerDirect Size	216 kB	216 kB	✓
Serverless pages/routerDirect gzip Size	56.8 kB	56.8 kB	⚠️ +3 B
Serverless pages/withRouter Size	216 kB	216 kB	✓
Serverless pages/withRouter gzip Size	56.8 kB	56.8 kB	⚠️ +3 B
Build Dir Size	1.31 MB	1.31 MB	✓
Average Memory Usage	142 MB	142 MB	⚠️ +910 kB
Max Memory Usage	199 MB	188 MB	-11.2 MB
Average CPU Usage	98.21%	94.95%	-3.26%
Max CPU Usage	111.11%	111.11%	✓
node_modules Size	42.7 MB	42.7 MB	✓

[timneutkens]

We could just run it on every commit to canary right? But for now this is fine 👍