upgrade CI workflow

.github/workflows/main.yaml

-name: Build and Test
+name: Main
 on:
   push:
   pull_request:
@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         os:
-          - ubuntu-18.04
+          - ubuntu-20.04
           - macOS-10.15
           - windows-2019
     steps:
@@ -34,7 +34,7 @@ jobs:
     strategy:
       matrix:
         os:
-          - ubuntu-18.04
+          - ubuntu-20.04
           - macOS-10.15
     needs: build
     steps:
@@ -44,27 +44,7 @@ jobs:
         run: brew install shunit2 icarus-verilog
       - name: Install Dependencies (Linux)
         if: runner.os == 'Linux'
-        run: sudo apt-get install -y shunit2 flex bison autoconf gperf
-      - name: Cache iverilog (Linux)
-        uses: actions/cache@v1
-        if: runner.os == 'Linux'
-        with:
-          path: ~/.local
-          key: ${{ runner.OS }}-iverilog-10-3
-          restore-keys: ${{ runner.OS }}-iverilog-10-3
-      - name: Install iverilog (Linux)
-        if: runner.os == 'Linux'
-        run: |
-          if [ ! -e "$HOME/.local/bin/iverilog" ]; then
-            curl -L https://github.com/steveicarus/iverilog/archive/v10_3.tar.gz > iverilog-10_3.tar.gz
-            tar -xzf iverilog-10_3.tar.gz
-            cd iverilog-10_3
-            autoconf
-            ./configure --prefix=$HOME/.local
-            make
-            make install
-            cd ..
-          fi
+        run: sudo apt-get install -y shunit2 iverilog
       - name: Download Artifact
         uses: actions/download-artifact@v1
         with:
@@ -77,7 +57,7 @@ jobs:
           make test
 
   release:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         name: [macOS, Linux, Windows]
@@ -90,7 +70,7 @@ jobs:
           name: ${{ matrix.name }}
           path: sv2v-${{ matrix.name }}
       - name: Mark Binary Executable
-        run: chmod +x */sv2v*
+        run: chmod +x */sv2v
       - name: Create ZIP
         run: zip -r sv2v-${{ matrix.name }} ./sv2v-${{ matrix.name }}
       - name: Upload Release Asset

.github/workflows/notice.yaml

@@ -9,7 +9,7 @@ on:
       - NOTICE
 jobs:
   notice:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v1
       - uses: mstksg/setup-stack@v2

README.md

@@ -44,8 +44,8 @@ All of sv2v's dependencies are free and open-source.
 
 ### Pre-built binaries
 
-Binaries for Linux and macOS are available on the [releases page]. If your
-system is not covered, or you would like to build the latest commit, simple
+Binaries for Ubuntu, macOS, and Windows are available on the [releases page]. If
+your system is not covered, or you would like to build the latest commit, simple
 instructions for building from source are below.
 
 [releases page]: https://github.com/zachjs/sv2v/releases
@@ -122,7 +122,7 @@ front end if there is significant interest.
 ## Testing
 
 Once the [test dependencies](#dependencies) are installed, tests can be run with
-`make test`. Travis CI is used to automatically test commits on GitHub.
+`make test`. GitHub Actions is used to automatically test commits.
 
 There is also a [SystemVerilog compliance suite] being created to test
 open-source tools' SystemVerilog support. Although not every test in the suite