Refactor notation: degK to K (#1475)

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### Pull Request Checklist:
- [ ] This PR addresses an already opened issue (for bug fixes /
features)
    - This PR fixes #xyz
- [ ] Tests for the changes have been added (for bug fixes / features)
- [ ] (If applicable) Documentation has been added / updated (for bug
fixes / features)
- [ ] CHANGES.rst has been updated (with summary of main changes)
- [ ] Link to issue (:issue:`number`) and pull request (:pull:`number`)
has been added

### What kind of change does this PR introduce?

* "degK" is replaced with "K" where this remains

### Does this PR introduce a breaking change?

No

### Other information:

CHANGES.rst

@@ -2,6 +2,14 @@
 Changelog
 =========
 
+v0.46.0
+--------------------
+Contributors to this version: Éric Dupuis (:user:`coxipi`).
+
+Internal changes
+^^^^^^^^^^^^^^^^
+* Change "degK" to "K" used to design Kelvin units. (:pull:`1475`).
+
 v0.45.0 (2023-09-05)
 --------------------
 Contributors to this version: David Huard (:user:`huard`), Trevor James Smith (:user:`Zeitsperre`), Pascal Bourgault (:user:`aulemahal`), Juliette Lavoie (:user:`juliettelavoie`), Gabriel Rondeau-Genesse (:user:`RondeauG`), Marco Braun (:user:`vindelico`), Éric Dupuis (:user:`coxipi`).

xclim/indices/_conversion.py

@@ -395,9 +395,9 @@ def saturation_vapor_pressure(
     :cite:cts:`goff_low-pressure_1946,hardy_its-90_1998,sonntag_important_1990,tetens_uber_1930,vomel_saturation_2016,world_meteorological_organization_guide_2008`
     """
     if ice_thresh is not None:
-        thresh = convert_units_to(ice_thresh, "degK")
+        thresh = convert_units_to(ice_thresh, "K")
     else:
-        thresh = convert_units_to("0 K", "degK")
+        thresh = convert_units_to("0 K", "K")
     tas = convert_units_to(tas, "K")
     ref_is_water = tas > thresh
     if method in ["sonntag90", "SO90"]:
@@ -585,8 +585,8 @@ def relative_humidity(
     if method in ("bohren98", "BA90"):
         if tdps is None:
             raise ValueError("To use method 'bohren98' (BA98), dewpoint must be given.")
-        tdps = convert_units_to(tdps, "degK")
-        tas = convert_units_to(tas, "degK")
+        tdps = convert_units_to(tdps, "K")
+        tas = convert_units_to(tas, "K")
         L = 2.501e6
         Rw = (461.5,)
         hurs = 100 * np.exp(-L * (tas - tdps) / (Rw * tas * tdps))  # type: ignore
@@ -601,7 +601,7 @@ def relative_humidity(
     else:
         ps = convert_units_to(ps, "Pa")
         huss = convert_units_to(huss, "")
-        tas = convert_units_to(tas, "degK")
+        tas = convert_units_to(tas, "K")
 
         e_sat = saturation_vapor_pressure(tas=tas, ice_thresh=ice_thresh, method=method)
 
@@ -698,7 +698,7 @@ def specific_humidity(
     """
     ps = convert_units_to(ps, "Pa")
     hurs = convert_units_to(hurs, "")
-    tas = convert_units_to(tas, "degK")
+    tas = convert_units_to(tas, "K")
 
     e_sat = saturation_vapor_pressure(tas=tas, ice_thresh=ice_thresh, method=method)
 
@@ -844,7 +844,7 @@ def snowfall_approximation(
         prsn = pr * fraction.interp(tas=tas, method="linear")
 
     elif method == "auer":
-        dtas = convert_units_to(tas, "degK") - convert_units_to(thresh, "degK")
+        dtas = convert_units_to(tas, "K") - convert_units_to(thresh, "K")
 
         # Create nodes for the snowfall fraction: -inf, thresh, ..., thresh+6, inf [degC]
         t = np.concatenate(