Loosen pinned versions (rytilahti#781)

* Most of the cases depend now only on the same major version
* Special cases:
  * attrs: https://www.attrs.org/en/stable/backward-compatibility.html
  * pytz: uses YEAR.x format, considering we only use very basic API there should be no breakages
  * python ^3.6.5
  * construct ^2.10.56: was previously prone to break compatibility between any releases, but there has been no new releases for a while

pyproject.toml

@@ -22,38 +22,38 @@ miiocli = "miio.cli:create_cli"
 
 [tool.poetry.dependencies]
 python = "^3.6.5"
-click = "^7.1.1"
-cryptography = "^2.9"
+click = "^7"
+cryptography = "^2"
 construct = "^2.10.56"
-zeroconf = "^0.25.1"
-attrs = "^19.3.0"
-pytz = "^2019.3"
-appdirs = "^1.4.3"
-tqdm = "^4.45.0"
-netifaces = "^0.10.9"
-android_backup = { version = "^0.2", optional = true }
-importlib_metadata = "^1.6.0"
-croniter = "^0.3.32"
+zeroconf = "^0"
+attrs = "*"
+pytz = "*"
+appdirs = "^1"
+tqdm = "^4"
+netifaces = "^0"
+android_backup = { version = "^0", optional = true }
+importlib_metadata = "^1"
+croniter = "^0"
 
-sphinx = { version = "^3.1", optional = true }
-sphinx_click = { version = "^2.3", optional = true }
-sphinxcontrib-apidoc = { version = "^0.3.0", optional = true }
-sphinx_rtd_theme = { version = "^0.5.0", optional = true }
+sphinx = { version = "^3", optional = true }
+sphinx_click = { version = "^2", optional = true }
+sphinxcontrib-apidoc = { version = "^0", optional = true }
+sphinx_rtd_theme = { version = "^0", optional = true }
 
 [tool.poetry.extras]
 docs = ["sphinx", "sphinx_click", "sphinxcontrib-apidoc", "sphinx_rtd_theme"]
 
 [tool.poetry.dev-dependencies]
-pytest = "^5.4.1"
-pytest-cov = "^2.8.1"
-pytest-mock = "^3.1.0"
-voluptuous = "^0.11.7"
-pre-commit = "^2.2.0"
-doc8 = "^0.8.0"
-restructuredtext_lint = "^1.3.0"
-tox = "^3.14.6"
-isort = "^4.3.21"
-cffi = "^1.14.0"
+pytest = "^5"
+pytest-cov = "^2"
+pytest-mock = "^3"
+voluptuous = "^0"
+pre-commit = "^2"
+doc8 = "^0"
+restructuredtext_lint = "^1"
+tox = "^3"
+isort = "^4"
+cffi = "^1"
 
 [tool.isort]
 multi_line_output = 3