Instrumentation for asyncpg (#814)

Co-authored-by: Yusuke Tsutsumi <yusuke@tsutsumi.io>

tox.ini

@@ -116,6 +116,10 @@ envlist =
     py3{5,6,7,8}-test-ext-asgi
     pypy3-test-ext-asgi
 
+    ; opentelemetry-ext-asyncpg
+    py3{5,6,7,8}-test-ext-asyncpg
+    ; ext-asyncpg intentionally excluded from pypy3
+
     ; opentelemetry-ext-sqlite3
     py3{4,5,6,7,8}-test-ext-sqlite3
     pypy3-test-ext-sqlite3
@@ -217,6 +221,7 @@ changedir =
   test-ext-pymysql: ext/opentelemetry-ext-pymysql/tests
   test-ext-pyramid: ext/opentelemetry-ext-pyramid/tests
   test-ext-asgi: ext/opentelemetry-ext-asgi/tests
+  test-ext-asyncpg: ext/opentelemetry-ext-asyncpg/tests
   test-ext-sqlite3: ext/opentelemetry-ext-sqlite3/tests
   test-ext-wsgi: ext/opentelemetry-ext-wsgi/tests
   test-ext-zipkin: ext/opentelemetry-ext-zipkin/tests
@@ -253,6 +258,8 @@ commands_pre =
   wsgi,flask,django,pyramid: pip install {toxinidir}/ext/opentelemetry-ext-wsgi
   asgi,starlette: pip install {toxinidir}/ext/opentelemetry-ext-asgi
 
+  asyncpg: pip install {toxinidir}/ext/opentelemetry-ext-asyncpg
+
   boto: pip install {toxinidir}/ext/opentelemetry-ext-boto[test]
 
   flask: pip install {toxinidir}/ext/opentelemetry-ext-flask[test]
@@ -388,6 +395,7 @@ commands =
 [testenv:docker-tests]
 deps =
   pytest
+  asyncpg==0.20.1
   docker-compose >= 1.25.2
   mysql-connector-python ~=  8.0
   pymongo ~= 3.1
@@ -405,6 +413,7 @@ commands_pre =
               -e {toxinidir}/opentelemetry-sdk \
               -e {toxinidir}/opentelemetry-instrumentation \
               -e {toxinidir}/tests/util \
+              -e {toxinidir}/ext/opentelemetry-ext-asyncpg \
               -e {toxinidir}/ext/opentelemetry-ext-celery \
               -e {toxinidir}/ext/opentelemetry-ext-dbapi \
               -e {toxinidir}/ext/opentelemetry-ext-mysql \