Use newer Nunavut and fix minor doc styling issues (#165)

* Use newer Nunavut

* Fix minor documentation styling issues by upgrading to the latest theme & sphinx
diff --git a/docs/requirements.txt b/docs/requirements.txt
index 99ec183..6d0ab38 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -5,6 +5,6 @@
 # This file is meant to be used from the project root directory.
 
 .[transport_can_pythoncan,transport_serial,transport_udp]
-sphinx           == 3.4.1
-sphinx_rtd_theme == 0.5.0
+sphinx           == 3.5.4
+sphinx_rtd_theme == 0.5.2
 sphinx-computron >= 0.2.0
diff --git a/docs/static/custom.css b/docs/static/custom.css
index ec41fa0..60a6d51 100644
--- a/docs/static/custom.css
+++ b/docs/static/custom.css
@@ -20,14 +20,6 @@
     }
 }
 
-/* This is a dirty fix to the layout bug in the RTD theme; see https://github.com/readthedocs/sphinx_rtd_theme/issues/776 */
-.wy-menu-vertical li.toctree-l3 li.toctree-l4 li.toctree-l5                                                                        > a { padding-left:  7em; background: #ddd; }
-.wy-menu-vertical li.toctree-l3 li.toctree-l4 li.toctree-l5 li.toctree-l6                                                          > a { padding-left:  8em; background: #ccc; }
-.wy-menu-vertical li.toctree-l3 li.toctree-l4 li.toctree-l5 li.toctree-l6 li.toctree-l7                                            > a { padding-left:  9em; background: #bbb; }
-.wy-menu-vertical li.toctree-l3 li.toctree-l4 li.toctree-l5 li.toctree-l6 li.toctree-l7 li.toctree-l8                              > a { padding-left: 10em; background: #aaa; }
-.wy-menu-vertical li.toctree-l3 li.toctree-l4 li.toctree-l5 li.toctree-l6 li.toctree-l7 li.toctree-l8 li.toctree-l9                > a { padding-left: 11em; background: #999; }
-.wy-menu-vertical li.toctree-l3 li.toctree-l4 li.toctree-l5 li.toctree-l6 li.toctree-l7 li.toctree-l8 li.toctree-l9 li.toctree-l10 > a { padding-left: 12em; background: #888; }
-
 .wy-table-responsive table td,
 .wy-table-responsive table th {
     white-space: normal !important;
diff --git a/pyuavcan/VERSION b/pyuavcan/VERSION
index e8ea05d..c813fe1 100644
--- a/pyuavcan/VERSION
+++ b/pyuavcan/VERSION
@@ -1 +1 @@
-1.2.4
+1.2.5
diff --git a/setup.cfg b/setup.cfg
index d43d297..a53e0f7 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -56,7 +56,7 @@
 # Think thrice before adding anything here, please.
 # The preferred long-term plan is to avoid adding any new required dependencies whatsoever for the project's lifetime.
 install_requires =
-    nunavut ~= 1.1
+    nunavut ~= 1.2
     numpy   ~= 1.17, < 1.20
 # TODO: allow NumPy v1.20 -- requires fixing type annotations and many meaningless false-positives. No runtime effects.