tox: apply upper constraints to all non-pinned package installations

tests/upper-constraints.txt

@@ -1,8 +1,16 @@
 # Request the latest known version or newer of some dependencies to prevent the
 # pip dependency resolver from spending too much time backtracking.
 attrs>=20.2.0
+Automat>=0.8.0
+itemadapter>=0.1.1
+itemloaders>=1.0.3
+lxml>=4.6.1
+parsel>=1.5.2
 Pillow>=8.0.1
+pyOpenSSL>=20.0.0
 pytest>=6.2.1
 pytest-twisted>=1.13.1
+service_identity>=17.0.0
+six>=1.14.0
 sybil>=2.0.0
 Twisted>=19.10.0

tox.ini

@@ -9,7 +9,6 @@ minversion = 1.7.0
 
 [testenv]
 deps =
-    -ctests/constraints.txt
     -rtests/requirements-py3.txt
     # mitmproxy does not support PyPy
     # mitmproxy does not support Windows when running Python < 3.7
@@ -29,6 +28,8 @@ passenv =
 download = true
 commands =
     py.test --cov=scrapy --cov-report=xml --cov-report= {posargs:--durations=10 docs scrapy tests}
+install_command =
+    pip install -U -ctests/upper-constraints.txt {opts} {packages}
 
 [testenv:typing]
 basepython = python3
@@ -90,12 +91,15 @@ deps =
     Pillow==4.0.0
 setenv =
     _SCRAPY_PINNED=true
+install_command =
+    pip install -U {opts} {packages}
 
 [testenv:pinned]
 deps =
     {[pinned]deps}
     lxml==3.5.0
     PyDispatcher==2.0.5
+install_command = {[pinned]install_command}
 setenv =
     {[pinned]setenv}
 
@@ -107,6 +111,7 @@ deps =
     # not need to build lxml from sources in a CI Windows job:
     lxml==3.8.0
     PyDispatcher==2.0.5
+install_command = {[pinned]install_command}
 setenv =
     {[pinned]setenv}
 
@@ -123,6 +128,7 @@ commands =
 [testenv:asyncio-pinned]
 deps = {[testenv:pinned]deps}
 commands = {[testenv:asyncio]commands}
+install_command = {[pinned]install_command}
 setenv =
     {[pinned]setenv}
 
@@ -138,6 +144,7 @@ deps =
     lxml==4.0.0
     PyPyDispatcher==2.1.0
 commands = {[testenv:pypy3]commands}
+install_command = {[pinned]install_command}
 setenv =
     {[pinned]setenv}