MY hunch is that the problem was on the server-side. I didn’t have to do anything other than wait 2 days for this to fix itself.
(@v1.5) pkg> update
Updating registry at `C:\Users\jason\.julia\registries\General`
Installed URIs ─ v1.1.0
Installed HTTP ─ v0.9.2
Installed GR ─── v0.49.1
Updating `C:\Users\jason\.julia\environments\v1.5\Project.toml`
[5ae59095] ↑ Colors v0.12.4 ⇒ v0.12.6
[8f4d0f93] ↑ Conda v1.4.1 ⇒ v1.5.0
[a93c6f00] ↑ DataFrames v0.21.8 ⇒ v0.22.2
[7073ff75] ↑ IJulia v1.22.0 ⇒ v1.23.1
[91a5bcdd] ↑ Plots v1.7.3 ⇒ v1.9.1
Updating `C:\Users\jason\.julia\environments\v1.5\Manifest.toml`
[324d7699] ↑ CategoricalArrays v0.8.3 ⇒ v0.9.0
[35d6a980] ↑ ColorSchemes v3.10.1 ⇒ v3.10.2
[5ae59095] ↑ Colors v0.12.4 ⇒ v0.12.6
[34da2185] ↑ Compat v3.23.0 ⇒ v3.25.0
[8f4d0f93] ↑ Conda v1.4.1 ⇒ v1.5.0
[d38c429a] ↑ Contour v0.5.5 ⇒ v0.5.7
[a93c6f00] ↑ DataFrames v0.21.8 ⇒ v0.22.2
[59287772] ↑ Formatting v0.4.1 ⇒ v0.4.2
[28b8d3ca] ↓ GR v0.52.0 ⇒ v0.49.1
[5c1252a2] ↑ GeometryBasics v0.3.3 ⇒ v0.3.5
[4d00f742] - GeometryTypes v0.8.3
[cd3eb016] ↑ HTTP v0.8.19 ⇒ v0.9.2
[7073ff75] ↑ IJulia v1.22.0 ⇒ v1.23.1
[23fbe1c1] ↑ Latexify v0.14.2 ⇒ v0.14.7
[77ba4419] ↑ NaNMath v0.3.4 ⇒ v0.3.5
[69de0a69] ↑ Parsers v1.0.11 ⇒ v1.0.15
[995b91a9] ↑ PlotUtils v1.0.7 ⇒ v1.0.8
[91a5bcdd] ↑ Plots v1.7.3 ⇒ v1.9.1
[08abe8d2] + PrettyTables v0.10.1
[3cdcf5f2] ↑ RecipesBase v1.1.0 ⇒ v1.1.1
[01d81517] ↑ RecipesPipeline v0.1.13 ⇒ v0.2.1
[ae029012] ↑ Requires v1.1.0 ⇒ v1.1.2
[90137ffa] ↑ StaticArrays v0.12.5 ⇒ v1.0.1
[856f2bd8] ↑ StructTypes v1.1.0 ⇒ v1.2.1
[bd369af6] ↑ Tables v1.1.0 ⇒ v1.2.2
[5c2747f8] + URIs v1.1.0
Building GR → `C:\Users\jason\.julia\packages\GR\cRdXQ\deps\build.log`
(@v1.5) pkg> update
Updating registry at `C:\Users\jason\.julia\registries\General`
No Changes to `C:\Users\jason\.julia\environments\v1.5\Project.toml`
No Changes to `C:\Users\jason\.julia\environments\v1.5\Manifest.toml`